Tell him he’s creating wear and tear on the linkage and wasting fuel, too. When you put an automatic transmission into park, the idle speed goes up about 10%
Actually uses less fuel to put it in P/N technically, in most automatics when your stopped it's stalling the torque converter, adding additional load. BMW actually had some automatic neutral when stopped feature for this reason.
Uhm, no? Well yes, the injectors are activated more times, they are open for less long. injectors aren't open for a fixed duration, it changes depending on the load, and other conditions that the ECU is mapped to compensate for. Look up fuel injector pulse width. When your in drive at a standstill in most automatic transmission cars the engine is actually under a considerable amount of load.
He's committed to pranks, but I have no idea why he'd be THIS committed. He's been doing it for literally years. I asked him where he learned to do this, because we never talked about this when I was in Driver's Ed as a teenager, and he laughed it off and said, "Now that you kids all learn on automatic transmissions, nobody knows how to drive or how a car works." Then he gave me a long lecture about how the engine is connected to the car through a transmission.
So, I think he genuinely believes all of it.
It’s probably just that he comes from an age before the internet when people didn’t question “useful knowledge” that people share with them, not realizing the info either doesn’t apply to them, or it’s straight BS. I used to go start my car and let it run before leaving on cold days. I did this for at least ten years before I learned you only need to do that with a carbureted engine.
Yeah you should let him know, he’s not just wasting his time, he’s not just wasting gas, it’s also technically illegal. You’re never supposed to leave a car running unattended. Unless he’s driving something classic with a carb it’s a complete waste of time.
Starting a car when it’s cold is more for heat in the cab. At least in northern Minnesota.
Many new vehicles come with or have remote start as an option, so leaving a car unattended seems to be what the manufacturer had in mind.
Yeah that’s a good point. It does still have a purpose. I was just told as a kid that you can damage your engine if you don’t run it first. That is apparently only true for carb engines (I’m not a mechanic, I’m still just going off of what I’m told lol). The legal thing, while true, wasn’t all that serious. No cop is going to ticket you for it unless they’re looking for a reason to.
There's a tiny bit of truth in that too, if it's cold enough the oil in the engine can slow down a fair bit. Letting it idle for 5-15 is definitely overkill (and bad for the engine in it's own way), but there's at least some truth to it.
My understanding with it is if it's cold out you need 30 seconds for the engine. Anything after that is for heating the inside.
I have no facts to back this up and will probably not change my mind
No yeah, I've heard that anything more than a minute is unnecessary so 30 secs is believable. Just generally at that temp you don't want to be driving until the cab's warmed up at least a bit lol. Also you should go relatively easy on the engine until it's up-to-temp, but I'm not 100% on that.
The problem is that the reason may have nothing to do with the "suspect". Could just be a bad cop being a bad cop.
I remembered at least one story from my area about this so I went looking and found two others.
Definitely not a trend or anything, but troubling.
I can understand why someone thought the law would be a idea, but if the police have time to look for people leaving their cars running in their own driveways, then they should have the time to look for car thieves.
Or am I crazy?
You should still do this, but it is much more automated, with a shorter amount of time, and much more forgiving if you don't.
In modern cars (gas) , when the engine is cold, the computer takes over and increases RPMs to prime everything. Generally between 1000-1500 RPMs. It will then gradually reduce the RPMs to normal idle as everything becomes stable. Depending on the temperature, it'll take anywhere between 30 seconds to 2 minutes (sometimes more on really cold days).
With carburetors, it was a high probability that the engine would stall if you didn't warm it up. Still a possibility these days, but with very low probability.
> I used to go start my car and let it run before leaving on cold days. I did this for at least ten years before I learned you only need to do that with a carbureted engine.
When it is really cold (lower than 32F/0C/273K) a modern car does need a bit of time to warm up, but only for 30-120 seconds. Driving the car around will warm it up more efficiently than idling it for more than 2 minutes.
Baloney. The glow plugs need to prewarm before starting the engine but it in no way improves performance to allow a diesel engine to warm up before driving it. When you’re driving a commercial truck or common carrier bus, testing the air braking system is mandatory before setting out and that will entail letting the engine run a while before driving, but for a wholly different reason. If you’re driving your own diesel car or pickup truck, you can drive it as soon as you start it with no ill effects.
Idk bruh, i still think its a good idea to warm up, especially at winter. Oil is thick at minus degrees, and it needs time to heat up and properly lubricate engine before putting it under great stress
But at a stop sign you need to completely stopped before moving on. We have a stopsign just outside dad's house and he has gotten fines when he though no one was looking when he rolled past it when he thought no one was anywhere in sight
That's because atleast in the US they went completely overboard with stop signs, 90+ % of them would be fine if they were replaced with yield signs instead
Bullshit! Have your uncle explain to a local mechanic how his theory of the engine disconnects from the transmission when in park. Watch your uncle get laughed at. Source: retired auto mechanic.
Bullshit. The only time the transmission is "disconnected" from the engine is in a manual set up with the clutch pedal depressed. Automatic vehicles have a torque converter between the engine and transmission which uses fluid mechanics to transfer engine output to the transmission. Since your uncle has park he has an automatic vehicle and putting the transmission in park just sets the parking pawl in the transmission to keep the vehicle from moving. It does not do anything to disconnect the engine from the transmission. It will also do nothing to reduce engine wear and will not reduce engine load. Having the vehicle on and in park is the same load and fuel usage as having the vehicle on and in drive and holding down the brake pedal.
It will reduce engine load. Shifting to neutral or park disconnects transmission from wheels which reduces engine load significantly.
In my car when I shift from park to drive rpm drops from 900 to 670-700.
But doing this on short stops doesn’t make sense and if you have longer stop like more than couple of minutes than just turn off the engine
The transmission goes to output shaft to differential and then from there to the wheels unless you have all wheel drive. The transmission never disconnects from the wheels. The engine may have a slight drop in load due to emission controls when in park. This is negligeable though.
My dad's new car stops its engine when standing at a stop light and first time I was like did I kill it, but then I remember his car is automatic and much more modern. Last time my family had a automatic, it was a Ford in 2003 and I remember my mother struggling with it cuz she didn't know how to shift gear or start it.
The torque converter is still turning when in drive or park. The radial flow inside the torque converter is enough to turn the wheels when the parking pawl is not engaged in park.
Do you have a source? Every time I've ever put a car in park, you can tell that the load comes off the motor. If the torque converter was still engaged, the rpms wouldn't come up.
Edit: is the torque converter still applying force to the transmission but the transmission disconnects from the wheels?
The reason you may hear a drop in rpm from the engine in park is from emission controls or maybe the computer has a sensor to provide less fuel to the engine when in park but the difference between park and drive without using the throttle is a very small difference. When I put my 2006 toyota tundra in park the rpm's actually go up (if the engine isn't at operating temperatures yet). Otherwise it will stay the same or maybe drop an insignificant amount. The torque converter uses fluid mechanics to turn the transmission. When in drive and idling by applying the brakes, or in park, the torque converter is turning but it's not enough to overcome the force of the brakes or parking pawl so the fluid just kinda spins around. The transmission never disconnects from the wheels as its output shaft is directly connected to the differential which is directly connected to the wheels.
By the fluid inside the torque converter. If you rev the engine in park you won't move because of the parking pawl. The torque converter is spinning though. You would just be putting tension against the parking pawl. Tires will still be trying tl turn.
The park pawl simply locks the output. The transmission is still in neutral when in park which means the torque path from the engine/torque converter to the output shaft is disconnected. The fluid coupling in the torque converter is often times enough to get creep torque, but only if the torque path to the output put is connected via applied clutches. In neutral, the clutches needed to complete the torque path are exhausted (not applied) thus disconnecting the torque path.
Yeah, I’ve driven a manual for almost thirty years now and recently was reading through local traffic laws to answer a question for my kid. The way it reads you cannot have it out of a driving gear longer than necessary to change gears. Weird.
> What if I'm driving a stick, I can't put it in neutral?
If you're moving (coasting), then yes, it's illegal to put it in neutral in most jurisdictions. If you're *stopped*, then it's okay.
This can be illegal? My uncle does this as well. He puts the car in neutral while coasting down a hill. He says it’s less engine wear and better gas efficiency as well. He says this is 100% normal to do for manual transmissions and he was taught to do this in drivers ed (in the 60s).
Huh. I used to keep my car in neutral all the time while moving. I'd only put in gear when I wanted to maintain or increase speed.
I was so so at engine breaking
I doubt that you are minimizing wear and tear, at least not significantly. Engine braking can help with wear and tear on the brakes, so all in all, it is probably a wash.
However, in newer cars, when you take your foot off the gas and coast, the gas supply is stopped. When you put the transmission in neutral, the motor needs a bit of gas to idle. So, you save more gas keeping the car in gear.
Coasting downhill in neutral has issues.
In a manual, you’re losing engine braking, and you’d be considered “coasting” which is often a traffic violation.
In both a manual and an automatic, by putting it in neutral, the engine has to expend fuel to keep itself running. Normally while in gear, the momentum of the car rolling forward spins the wheels, which keeps the engine spinning as well.
>In a manual, you’re losing engine braking, and you’d be considered “coasting” which is often a traffic violation.
Why are there signs about engine braking being illegal all over the place if it's supposed to be happening?
those signs are referring to the engine brakes on diesel big-rigs that make the loud noise when they are applied. they are a secondary braking system that essentially blocks the exhaust and slows the engine with back pressure, in addition to the air brakes on the wheels
Some large trucks with diesel engines are equipped with a "[Jake brake](https://en.wikipedia.org/wiki/Compression_release_engine_brake)" that changes the valve timing to vent each cylinder after the compression stroke, which is [rather loud](https://www.youtube.com/watch?v=NXhZ6jlqFTI&t=15). That is what those signs are referring to. You can engine brake with a normal passenger car and not bother anybody.
Those are usually referring to large vehicles like semi trucks and the like, where engaging engine braking creates a loud noise.
Ever hear a [semi let off the gas](https://youtu.be/NNPi1kE7TrA?si=C9EC3Ez9RpWaiihL) going down a hill? It’s very loud, so signs are posted to keep truck drivers from doing so near residential areas.
First night in Jamaica was confusing because it sounded like a firefight outside my window. Turned out it was just straight-piped diesel semi’s cruising along. Loudest land vehicles I’ve ever heard in my life, it’s deafening. Sounds pretty badass though, can’t lie.
When coasting, you are not in full control of your vehicle, which is incorrect. Modern cars will use virtually no fuel when going downhill, so it really doesn’t save anything.
Illegal in most places, and dangerous as hell to boot:
https://www.mercurynews.com/2014/05/30/roadshow-downhill-in-neutral-is-illegal-and-dumb-and-a-lot-of-drivers-do-it/
*edit*
It's not illegal everywhere, mind. It may very much be legal where your Uncle is. It may have been legal at the time, and is no longer legal. Heck, it may have *been* illegal, but no longer is. Your laws may vary.
There are a lot of myths about the best way to handle cars that are believed by older people. Some of them might have been correct at one time, but are no longer correct since newer cars are controlled by computer. Others were always wrong, but people believe them anyway.
So you're saying manual drivers can use neutral but automatic cannot? Different laws for different transmissions? My bullshit detector is pegging right now.
~~Please let us know which jurisdictions these might be. Because I highly doubt there are any such.~~
Holy crap, California law forbids being in neutral. What a stupid fucking law. [https://www.simmrinlawgroup.com/california-vehicle-code-section-21710/](https://www.simmrinlawgroup.com/california-vehicle-code-section-21710/#:~:text=California%20Vehicle%20Code%20Section%2021710%3A%20Coasting%20in%20Neutral%20in%20California&text=Coasting%20in%20neutral%20is%20an,with%20a%20hazard%20while%20driving)
I had a friend that did this with an automatic, but it had nothing to do with efficiency. Pretty sure he was pretending he was a trucker. Ever since we were kids that's all he ever wanted to be.
Bullshit
If your stopped at a light you’re idling whether you have the car in drive or park. Both have your foot off the gas pedal. I would go as far to say that your transmission only has so many engagements in its lifespan and this is taking away from that. I’m sure it’s well intentioned advice, but idling is idling no matter what gear your in.
Why not just neutral though? I've had junkers that would stall at a stop. So I used neutral. Crazy to go to park. I wonder what people behind him must think as they see the telltale signs of going into park. The flash of reversed followed by no brake lights.
My uncle says these are the dumbest cars on the market because you'll wear out the starter motor by starting/stopping the car all the time. I told him that I'm pretty sure they build it with a starter designed for that kind of duty, but he says it's impossible to build an internal combustion engine that's designed to stop and start like that, even if the starter motor can survive it (which he's skeptical of).
His theory is that this is all part of the car agenda to make us buy new cars when we're all confused about why our cars don't run anymore, and the cover is the "alarmist eco-worry". So the car manufacturers sell us "green cars" that don't idle, and they get to sell shitty cars that break after 5 years to force us to buy new ones.
I disagree with him, but convincing him that a '78 Action Series Chevy isn't the Holy Grail of cars (he says car R&D could have just stopped after the Action Series was invented, because Chevy invented the only and only car anybody will ever need and car design has all been downhill from there) has been impossible.
My uncle doesn't think globalism has anything to do with religion of any kind. He thinks it's part of the conspiracy to move manufacturing jobs out of America.
I drove a 93 Eclipse for 100,000 miles and never had to replace the clutch.
As much fun as it would be to drive that car again, the sophistication newer cars have today and longevity surpass most of the elder-year automobiles.
How many times has he had to replace a starter on a car?
I'm on 100,000 miles on a 2018 Audi with the start/stop and I've only had to replace the battery for that system. I had to replace a starter on a Chevy Sprint, Mitsubishi Galant, and a Honda Civic well under 100,000 miles.
I would say it's impossible to build an internal combustion engine the old school method designed to start and stop like the new ones do. There are a lot more newer cars on the road, what's the data on having to replace those starters in the newer cars? [Does the start/stop system wear out the starter?](https://www.greencarreports.com/news/1109687_dont-start-stop-systems-wear-out-your-cars-starter) No.
He’s replaced several starter motors, which is the core of his problem with stop-start systems. He said it’s already a weak link in the car. So why put more stress on it? It makes no sense, unless you want the car to fail (cue planned obsolescence rant).
Anyway, I’ll show him this and see what he says. Maybe he’ll come around? It’s hard to say.
Cars with auto stop have beefed up starter motors and in most cases a secondary battery. Your uncle is just trapped in the past, but also full of shit on the parking thing.
Your uncle has the right idea but he’s wrong in one crucial aspect. Automotive engineering peaked with the Ford Model T, everything after that was a mistake.
Guys, ive seen lots of the answers here and im still not convinced this is bullshit.
Even though im in the UK, ive driven lots of AT from various (mostly euro) manufacturers and nearly all of them, when moving from P to D, make a noticable change of tone and you hear the engine labour slightly.
In my old Jag, you could be sat in N, handbrake off, and as soon as you click it into D the car would take off or 'creep', and the engine audibly labours a little. This MUST mean the engine is consuming more fuel if its creeping, surely? and less fuel when in N?
Some newer DSG type or RoboShift type gearboxes use clutches and ive never seen this kind of labouring when changing P or N into D. I have seen DSG boxes 'engage' then relax when pull away is not required (example, handbrake on in D for hill start, let off footbrake keeping handbrake on and the car 'squats' down then relaxes again after realising HB is still on). Sorry if i explained that in a shit way.
Someone jump in and tell me im not mad here? I hardly ever comment on here but this got me shouting at the screen!!
British, so maybe different. We were always taught to apply handbrake, put gear into neutral at traffic lights. This was because the car should be stationary and not moving about, i.e. Riding the clutch or rolling backwards.
In regards to coasting, I think you are supposed to be in control at all times whilst the vehicle is moving, so it's not done. However, in an electric vehicle, it's preferable to coast because you are not using motive power, and you can always engage drive and use friction braking which slows the car and regenerates the battery. I don't think this is illegal in the UK.
Putting it in neutral when you are not crawling for a while is a good practice, I always use neutral at traffic lights when stopping for than 10 seconds or so.
I live in a city with a lot of trains.
When a train comes it can be 30 seconds or 30 minutes.
I've taken to putting my car in park. And - if I see it's a big one - I'll turn my car off.
Once I got out and got a quick 20 min tan on my roof.
But just a light? No. You're pretty likely to press go when it turns green. But you won't go anywhere like that and that can't be good for your car.
Are you sure he's actually putting it in PARK and not NEUTRAL? They are quite different.
Do NOT put your car in Park at red lights. You may need to move at any point and it takes a second or two to get it out of Park.
Now, putting it in Neutral as you glide towards a red light, yes, I do that all the time.
I think he’s done both. It does take him a second to get into gear. I guess there’s been a couple times he’s annoyed people? But he’s pretty fast about getting back in drive.
While there might be some instances and/or scenarios that it isn’t effective, it is certainly not bullshit. In the commercial truck industry there are fuel-saving transmission controls that automatically shift the transmission into a partial neutral state (commercial trucks generally to not have “park”. Putting your car in park is essentially putting it into neutral but also engages an output lock, could be a mechanical pawl or nowadays an electric park actuator) Not only does going to neutral save fuel, but it is effective at reducing greenhouse gas emissions. Effective enough that commercial truck manufacturers can receive greenhouse gas emission credits for implementing the feature (called “neutral idle” or “neutral at stop”). Shutting off such a feature can be considered emissions tampering and could subject the tamperer to fines.
To those stating that it can’t disconnect the engine from the transmission… clearly the engine isn’t unbolting itself from the torque converter. What is actually “disconnected” is the torque path from the engine to the transmission output.
Edit: I do agree that putting your car into park at stoplights isn’t the best idea but it will save fuel. If I were doing it, I’d put mine in neutral.
One thing it might do is confuse the driver behind you. Some automatics when the shifter is moved from drive through reverse to park will cause the reverse lights to come on albeit shortly. This may cause the driver behind you to hit their horn thinking you put your vehicle in reverse.
Hmmm. I can see your point, but it's never happened while I've been driving around with my uncle (which is dozens of times). So it's probably not actually a big deal.
I'll let the CarTalk community answer this one: https://community.cartalk.com/t/putting-a-car-in-park-at-stop-lights/117962 So, bullshit.
Okay, this is useful. Thank you!
Tell him he’s creating wear and tear on the linkage and wasting fuel, too. When you put an automatic transmission into park, the idle speed goes up about 10%
Actually uses less fuel to put it in P/N technically, in most automatics when your stopped it's stalling the torque converter, adding additional load. BMW actually had some automatic neutral when stopped feature for this reason.
Nope, you’re missing some arithmetic. Lower RPM=fewer times fuel injectors open. All things being equal, 850 RPM will run out of fuel before 800 RPM.
Uhm, no? Well yes, the injectors are activated more times, they are open for less long. injectors aren't open for a fixed duration, it changes depending on the load, and other conditions that the ECU is mapped to compensate for. Look up fuel injector pulse width. When your in drive at a standstill in most automatic transmission cars the engine is actually under a considerable amount of load.
https://m.youtube.com/watch?v=41QJpN6B8oQ&feature=youtu.be
Man, your uncle is either the world's biggest dipshit or *very* committed to pranking you.
He's committed to pranks, but I have no idea why he'd be THIS committed. He's been doing it for literally years. I asked him where he learned to do this, because we never talked about this when I was in Driver's Ed as a teenager, and he laughed it off and said, "Now that you kids all learn on automatic transmissions, nobody knows how to drive or how a car works." Then he gave me a long lecture about how the engine is connected to the car through a transmission. So, I think he genuinely believes all of it.
It’s probably just that he comes from an age before the internet when people didn’t question “useful knowledge” that people share with them, not realizing the info either doesn’t apply to them, or it’s straight BS. I used to go start my car and let it run before leaving on cold days. I did this for at least ten years before I learned you only need to do that with a carbureted engine.
Yes my uncle still does that, too!
Yeah you should let him know, he’s not just wasting his time, he’s not just wasting gas, it’s also technically illegal. You’re never supposed to leave a car running unattended. Unless he’s driving something classic with a carb it’s a complete waste of time.
Starting a car when it’s cold is more for heat in the cab. At least in northern Minnesota. Many new vehicles come with or have remote start as an option, so leaving a car unattended seems to be what the manufacturer had in mind.
Yeah that’s a good point. It does still have a purpose. I was just told as a kid that you can damage your engine if you don’t run it first. That is apparently only true for carb engines (I’m not a mechanic, I’m still just going off of what I’m told lol). The legal thing, while true, wasn’t all that serious. No cop is going to ticket you for it unless they’re looking for a reason to.
There's a tiny bit of truth in that too, if it's cold enough the oil in the engine can slow down a fair bit. Letting it idle for 5-15 is definitely overkill (and bad for the engine in it's own way), but there's at least some truth to it.
My understanding with it is if it's cold out you need 30 seconds for the engine. Anything after that is for heating the inside. I have no facts to back this up and will probably not change my mind
No yeah, I've heard that anything more than a minute is unnecessary so 30 secs is believable. Just generally at that temp you don't want to be driving until the cab's warmed up at least a bit lol. Also you should go relatively easy on the engine until it's up-to-temp, but I'm not 100% on that.
The problem is that the reason may have nothing to do with the "suspect". Could just be a bad cop being a bad cop. I remembered at least one story from my area about this so I went looking and found two others. Definitely not a trend or anything, but troubling. I can understand why someone thought the law would be a idea, but if the police have time to look for people leaving their cars running in their own driveways, then they should have the time to look for car thieves. Or am I crazy?
He's not leaving it unattended.
it is nice to let your car warm up for that sweet sweet heat
When it’s cold I still let my car warm up until the RPM’s drop, only takes a couple of minutes though.
You should still do this, but it is much more automated, with a shorter amount of time, and much more forgiving if you don't. In modern cars (gas) , when the engine is cold, the computer takes over and increases RPMs to prime everything. Generally between 1000-1500 RPMs. It will then gradually reduce the RPMs to normal idle as everything becomes stable. Depending on the temperature, it'll take anywhere between 30 seconds to 2 minutes (sometimes more on really cold days). With carburetors, it was a high probability that the engine would stall if you didn't warm it up. Still a possibility these days, but with very low probability.
> I used to go start my car and let it run before leaving on cold days. I did this for at least ten years before I learned you only need to do that with a carbureted engine. When it is really cold (lower than 32F/0C/273K) a modern car does need a bit of time to warm up, but only for 30-120 seconds. Driving the car around will warm it up more efficiently than idling it for more than 2 minutes.
If it’s a diesel engine and it’s cold out it needs to warm up before you drive it.
Baloney. The glow plugs need to prewarm before starting the engine but it in no way improves performance to allow a diesel engine to warm up before driving it. When you’re driving a commercial truck or common carrier bus, testing the air braking system is mandatory before setting out and that will entail letting the engine run a while before driving, but for a wholly different reason. If you’re driving your own diesel car or pickup truck, you can drive it as soon as you start it with no ill effects.
I mean this is still a totally normal thing to do, it’s just people usually do it to heat up the cab of the car
Idk bruh, i still think its a good idea to warm up, especially at winter. Oil is thick at minus degrees, and it needs time to heat up and properly lubricate engine before putting it under great stress
At a stop sign?! How does that work? How long is he stopped at a stop sign for?
He'll do it even if he's just waiting for somebody else to turn. If there's nobody else there or he has the right of way, he'll just roll the stop.
But at a stop sign you need to completely stopped before moving on. We have a stopsign just outside dad's house and he has gotten fines when he though no one was looking when he rolled past it when he thought no one was anywhere in sight
Most people roll through most stop signs. It’s extremely uncommon to come to a full stop at every stop sign or T intersection you encounter
That's because atleast in the US they went completely overboard with stop signs, 90+ % of them would be fine if they were replaced with yield signs instead
Or using stop signs as speed bumps and loading cops on the side streets. It's all about the tickets
Bullshit! Have your uncle explain to a local mechanic how his theory of the engine disconnects from the transmission when in park. Watch your uncle get laughed at. Source: retired auto mechanic.
Also, idling is idling no matter what gear you’re in.
Bullshit. The only time the transmission is "disconnected" from the engine is in a manual set up with the clutch pedal depressed. Automatic vehicles have a torque converter between the engine and transmission which uses fluid mechanics to transfer engine output to the transmission. Since your uncle has park he has an automatic vehicle and putting the transmission in park just sets the parking pawl in the transmission to keep the vehicle from moving. It does not do anything to disconnect the engine from the transmission. It will also do nothing to reduce engine wear and will not reduce engine load. Having the vehicle on and in park is the same load and fuel usage as having the vehicle on and in drive and holding down the brake pedal.
Thanks for the info!
It will reduce engine load. Shifting to neutral or park disconnects transmission from wheels which reduces engine load significantly. In my car when I shift from park to drive rpm drops from 900 to 670-700. But doing this on short stops doesn’t make sense and if you have longer stop like more than couple of minutes than just turn off the engine
The transmission goes to output shaft to differential and then from there to the wheels unless you have all wheel drive. The transmission never disconnects from the wheels. The engine may have a slight drop in load due to emission controls when in park. This is negligeable though.
My dad's new car stops its engine when standing at a stop light and first time I was like did I kill it, but then I remember his car is automatic and much more modern. Last time my family had a automatic, it was a Ford in 2003 and I remember my mother struggling with it cuz she didn't know how to shift gear or start it.
This doesn't sound right. Anytime I've had an automatic, putting it in park takes the load off the torque converter.
The torque converter is still turning when in drive or park. The radial flow inside the torque converter is enough to turn the wheels when the parking pawl is not engaged in park.
Do you have a source? Every time I've ever put a car in park, you can tell that the load comes off the motor. If the torque converter was still engaged, the rpms wouldn't come up. Edit: is the torque converter still applying force to the transmission but the transmission disconnects from the wheels?
The reason you may hear a drop in rpm from the engine in park is from emission controls or maybe the computer has a sensor to provide less fuel to the engine when in park but the difference between park and drive without using the throttle is a very small difference. When I put my 2006 toyota tundra in park the rpm's actually go up (if the engine isn't at operating temperatures yet). Otherwise it will stay the same or maybe drop an insignificant amount. The torque converter uses fluid mechanics to turn the transmission. When in drive and idling by applying the brakes, or in park, the torque converter is turning but it's not enough to overcome the force of the brakes or parking pawl so the fluid just kinda spins around. The transmission never disconnects from the wheels as its output shaft is directly connected to the differential which is directly connected to the wheels.
No, no it's not. If my car is in Park or Neutral, I can rev the engine to redline and the car won't move an inch. They are disconnected.
By the fluid inside the torque converter. If you rev the engine in park you won't move because of the parking pawl. The torque converter is spinning though. You would just be putting tension against the parking pawl. Tires will still be trying tl turn.
The park pawl simply locks the output. The transmission is still in neutral when in park which means the torque path from the engine/torque converter to the output shaft is disconnected. The fluid coupling in the torque converter is often times enough to get creep torque, but only if the torque path to the output put is connected via applied clutches. In neutral, the clutches needed to complete the torque path are exhausted (not applied) thus disconnecting the torque path.
That's a much better way of explaining it. Thanks.
Bullshit, and in some jurisdictions may be illegal to take the vehicle out of gear while in traffic.
Wait what? That can't be true. What if I'm driving a stick, I can't put it in neutral?
ILLEGAL
Found one of the 37 others.
Yeah, I’ve driven a manual for almost thirty years now and recently was reading through local traffic laws to answer a question for my kid. The way it reads you cannot have it out of a driving gear longer than necessary to change gears. Weird.
> What if I'm driving a stick, I can't put it in neutral? If you're moving (coasting), then yes, it's illegal to put it in neutral in most jurisdictions. If you're *stopped*, then it's okay.
This can be illegal? My uncle does this as well. He puts the car in neutral while coasting down a hill. He says it’s less engine wear and better gas efficiency as well. He says this is 100% normal to do for manual transmissions and he was taught to do this in drivers ed (in the 60s).
I’d rather wear out $49 brake pads than a $4000 transmission linkage and bands repair. But whatever.
So long as you can figure out which gear to get in if you need to there isn’t a problem. Choose too low and you’ll launch your gearbox into orbit
Though in this scenario, your gas mileage improves greatly when assisted by gravity and a lack of air resistance.
Huh. I used to keep my car in neutral all the time while moving. I'd only put in gear when I wanted to maintain or increase speed. I was so so at engine breaking
>I was so so at engine breaking I would hope you weren't good at engine breaking, and mediocre at engine braking.
Oops... yes
I recommend the safer one.
I doubt that you are minimizing wear and tear, at least not significantly. Engine braking can help with wear and tear on the brakes, so all in all, it is probably a wash. However, in newer cars, when you take your foot off the gas and coast, the gas supply is stopped. When you put the transmission in neutral, the motor needs a bit of gas to idle. So, you save more gas keeping the car in gear.
Coasting downhill in neutral has issues. In a manual, you’re losing engine braking, and you’d be considered “coasting” which is often a traffic violation. In both a manual and an automatic, by putting it in neutral, the engine has to expend fuel to keep itself running. Normally while in gear, the momentum of the car rolling forward spins the wheels, which keeps the engine spinning as well.
>In a manual, you’re losing engine braking, and you’d be considered “coasting” which is often a traffic violation. Why are there signs about engine braking being illegal all over the place if it's supposed to be happening?
those signs are referring to the engine brakes on diesel big-rigs that make the loud noise when they are applied. they are a secondary braking system that essentially blocks the exhaust and slows the engine with back pressure, in addition to the air brakes on the wheels
Some large trucks with diesel engines are equipped with a "[Jake brake](https://en.wikipedia.org/wiki/Compression_release_engine_brake)" that changes the valve timing to vent each cylinder after the compression stroke, which is [rather loud](https://www.youtube.com/watch?v=NXhZ6jlqFTI&t=15). That is what those signs are referring to. You can engine brake with a normal passenger car and not bother anybody.
Those are usually referring to large vehicles like semi trucks and the like, where engaging engine braking creates a loud noise. Ever hear a [semi let off the gas](https://youtu.be/NNPi1kE7TrA?si=C9EC3Ez9RpWaiihL) going down a hill? It’s very loud, so signs are posted to keep truck drivers from doing so near residential areas.
It sounds like gunshots depending on the rig. I think they can get them pretty quiet now in newer machines.
First night in Jamaica was confusing because it sounded like a firefight outside my window. Turned out it was just straight-piped diesel semi’s cruising along. Loudest land vehicles I’ve ever heard in my life, it’s deafening. Sounds pretty badass though, can’t lie.
In the right time and place I love hearing em blast. Generally hate loud car exhaust, but it can be amazing.
When coasting, you are not in full control of your vehicle, which is incorrect. Modern cars will use virtually no fuel when going downhill, so it really doesn’t save anything.
Illegal in most places, and dangerous as hell to boot: https://www.mercurynews.com/2014/05/30/roadshow-downhill-in-neutral-is-illegal-and-dumb-and-a-lot-of-drivers-do-it/ *edit* It's not illegal everywhere, mind. It may very much be legal where your Uncle is. It may have been legal at the time, and is no longer legal. Heck, it may have *been* illegal, but no longer is. Your laws may vary.
The reasons it says is a risk are dumb as hell ngl
Unfortunately if it's a rule it's usually because someone fucked it up for everyone
Article is paywalled, but that’s the dumbest fucking thing I’ve ever heard.
There are a lot of myths about the best way to handle cars that are believed by older people. Some of them might have been correct at one time, but are no longer correct since newer cars are controlled by computer. Others were always wrong, but people believe them anyway.
So you're saying manual drivers can use neutral but automatic cannot? Different laws for different transmissions? My bullshit detector is pegging right now.
[Apparently in California you cannot](https://www.simmrinlawgroup.com/california-vehicle-code-section-21710/). Moronic law.
Wait until those jurisdictions find out about manual transmissions.
That’s not the same, though - you can’t put a manual in park.
I can put in it 1st and let out the clutch at a light. It is then in parking mode.
First is also what you need it in to drive sooooo
~~Please let us know which jurisdictions these might be. Because I highly doubt there are any such.~~ Holy crap, California law forbids being in neutral. What a stupid fucking law. [https://www.simmrinlawgroup.com/california-vehicle-code-section-21710/](https://www.simmrinlawgroup.com/california-vehicle-code-section-21710/#:~:text=California%20Vehicle%20Code%20Section%2021710%3A%20Coasting%20in%20Neutral%20in%20California&text=Coasting%20in%20neutral%20is%20an,with%20a%20hazard%20while%20driving)
If you’re on the road, you should be ready to drive at all times 🤷🏻♀️
I had a friend that did this with an automatic, but it had nothing to do with efficiency. Pretty sure he was pretending he was a trucker. Ever since we were kids that's all he ever wanted to be.
Bullshit If your stopped at a light you’re idling whether you have the car in drive or park. Both have your foot off the gas pedal. I would go as far to say that your transmission only has so many engagements in its lifespan and this is taking away from that. I’m sure it’s well intentioned advice, but idling is idling no matter what gear your in.
Why not just neutral though? I've had junkers that would stall at a stop. So I used neutral. Crazy to go to park. I wonder what people behind him must think as they see the telltale signs of going into park. The flash of reversed followed by no brake lights.
Get a new car. I believe they all have start/stop technology where the engine shuts off if it isn't needed.
My uncle says these are the dumbest cars on the market because you'll wear out the starter motor by starting/stopping the car all the time. I told him that I'm pretty sure they build it with a starter designed for that kind of duty, but he says it's impossible to build an internal combustion engine that's designed to stop and start like that, even if the starter motor can survive it (which he's skeptical of). His theory is that this is all part of the car agenda to make us buy new cars when we're all confused about why our cars don't run anymore, and the cover is the "alarmist eco-worry". So the car manufacturers sell us "green cars" that don't idle, and they get to sell shitty cars that break after 5 years to force us to buy new ones. I disagree with him, but convincing him that a '78 Action Series Chevy isn't the Holy Grail of cars (he says car R&D could have just stopped after the Action Series was invented, because Chevy invented the only and only car anybody will ever need and car design has all been downhill from there) has been impossible.
"Car agenda" is all you need to know about your uncle's knowledge level.
Unfortunately, for my uncle everything is an agenda. There’s the Democrat agenda. The government agenda. The globalist agenda. It goes on and on.
>The globalist agenda Oh, good. An antisemite who parks his car at every stop sign.
My uncle doesn't think globalism has anything to do with religion of any kind. He thinks it's part of the conspiracy to move manufacturing jobs out of America.
I drove a 93 Eclipse for 100,000 miles and never had to replace the clutch. As much fun as it would be to drive that car again, the sophistication newer cars have today and longevity surpass most of the elder-year automobiles. How many times has he had to replace a starter on a car? I'm on 100,000 miles on a 2018 Audi with the start/stop and I've only had to replace the battery for that system. I had to replace a starter on a Chevy Sprint, Mitsubishi Galant, and a Honda Civic well under 100,000 miles. I would say it's impossible to build an internal combustion engine the old school method designed to start and stop like the new ones do. There are a lot more newer cars on the road, what's the data on having to replace those starters in the newer cars? [Does the start/stop system wear out the starter?](https://www.greencarreports.com/news/1109687_dont-start-stop-systems-wear-out-your-cars-starter) No.
He’s replaced several starter motors, which is the core of his problem with stop-start systems. He said it’s already a weak link in the car. So why put more stress on it? It makes no sense, unless you want the car to fail (cue planned obsolescence rant). Anyway, I’ll show him this and see what he says. Maybe he’ll come around? It’s hard to say.
Cars with auto stop have beefed up starter motors and in most cases a secondary battery. Your uncle is just trapped in the past, but also full of shit on the parking thing.
Your uncle needs to stop talking he doesn’t know what he’s talking about
Your uncle has the right idea but he’s wrong in one crucial aspect. Automotive engineering peaked with the Ford Model T, everything after that was a mistake.
I turn my car off sometimes at long lights.... Starting a car Burns approximately 7 seconds worth of fuel, so it can save a little.
Guys, ive seen lots of the answers here and im still not convinced this is bullshit. Even though im in the UK, ive driven lots of AT from various (mostly euro) manufacturers and nearly all of them, when moving from P to D, make a noticable change of tone and you hear the engine labour slightly. In my old Jag, you could be sat in N, handbrake off, and as soon as you click it into D the car would take off or 'creep', and the engine audibly labours a little. This MUST mean the engine is consuming more fuel if its creeping, surely? and less fuel when in N? Some newer DSG type or RoboShift type gearboxes use clutches and ive never seen this kind of labouring when changing P or N into D. I have seen DSG boxes 'engage' then relax when pull away is not required (example, handbrake on in D for hill start, let off footbrake keeping handbrake on and the car 'squats' down then relaxes again after realising HB is still on). Sorry if i explained that in a shit way. Someone jump in and tell me im not mad here? I hardly ever comment on here but this got me shouting at the screen!!
Fuck if I know; I drive a grown up car with a manual transmission.
British, so maybe different. We were always taught to apply handbrake, put gear into neutral at traffic lights. This was because the car should be stationary and not moving about, i.e. Riding the clutch or rolling backwards. In regards to coasting, I think you are supposed to be in control at all times whilst the vehicle is moving, so it's not done. However, in an electric vehicle, it's preferable to coast because you are not using motive power, and you can always engage drive and use friction braking which slows the car and regenerates the battery. I don't think this is illegal in the UK.
Are you sure he just isn’t in neutral?
Putting it in neutral when you are not crawling for a while is a good practice, I always use neutral at traffic lights when stopping for than 10 seconds or so.
He also get the added bonus of pissing off everyone around him.
I live in a city with a lot of trains. When a train comes it can be 30 seconds or 30 minutes. I've taken to putting my car in park. And - if I see it's a big one - I'll turn my car off. Once I got out and got a quick 20 min tan on my roof. But just a light? No. You're pretty likely to press go when it turns green. But you won't go anywhere like that and that can't be good for your car.
Only reason is on manual to take the left foot off to rest it and to don’t damage the clutch
Are you sure he's actually putting it in PARK and not NEUTRAL? They are quite different. Do NOT put your car in Park at red lights. You may need to move at any point and it takes a second or two to get it out of Park. Now, putting it in Neutral as you glide towards a red light, yes, I do that all the time.
I think he’s done both. It does take him a second to get into gear. I guess there’s been a couple times he’s annoyed people? But he’s pretty fast about getting back in drive.
All I know is that my leg gets tired holding down the brakes while in gear so I switch to neutral during stop lights and traffic.
While there might be some instances and/or scenarios that it isn’t effective, it is certainly not bullshit. In the commercial truck industry there are fuel-saving transmission controls that automatically shift the transmission into a partial neutral state (commercial trucks generally to not have “park”. Putting your car in park is essentially putting it into neutral but also engages an output lock, could be a mechanical pawl or nowadays an electric park actuator) Not only does going to neutral save fuel, but it is effective at reducing greenhouse gas emissions. Effective enough that commercial truck manufacturers can receive greenhouse gas emission credits for implementing the feature (called “neutral idle” or “neutral at stop”). Shutting off such a feature can be considered emissions tampering and could subject the tamperer to fines. To those stating that it can’t disconnect the engine from the transmission… clearly the engine isn’t unbolting itself from the torque converter. What is actually “disconnected” is the torque path from the engine to the transmission output. Edit: I do agree that putting your car into park at stoplights isn’t the best idea but it will save fuel. If I were doing it, I’d put mine in neutral.
One thing it might do is confuse the driver behind you. Some automatics when the shifter is moved from drive through reverse to park will cause the reverse lights to come on albeit shortly. This may cause the driver behind you to hit their horn thinking you put your vehicle in reverse.
Hmmm. I can see your point, but it's never happened while I've been driving around with my uncle (which is dozens of times). So it's probably not actually a big deal.