[Artifex]

The momentum of the car spins the wheels which, through the transmission, spin the engine. Have you ever ridden a bike that doesn't have have free-wheeling pedals? When you stop pedaling the pedals continue to turn (same concept.)

Perhaps I'm just not following you correctly, but :

vtecprelude is talking about putting the stick in neutral. In that state, the wheels and flywheel are not mechanically connected, regardless of clutch position. During that time, the engine will idle normally at ~800 RPM. I am having a hard time understanding why this is bad?

what makes it juvenile?

Less control, more dangerous (if you gain a lot of speed) and you burn more gas. Do it on your skateboard not in your car.

Again, how does this burn more fuel? The car should be idling at ~800 RPM. I am also not following the safety aspect. Your ability to brake the car is independent of whether the car is in gear. Braking distance is determined by vehicle mass and stopping friction.

Maybe you can explain to me more in detail.

 

[ME]

Again, how does this burn more fuel? The car should be idling at ~800 RPM.

I was talking about leaving the car in gear (foot off clutch) while you coast down the hill, in that case you're burning no fuel because the injectors are turned completely off. If you're in neutral the engine is actually above idle (depends on vehicle speed) and so you're burning fuel.

I am also not following the safety aspect. Your ability to brake the car is independent of whether the car is in gear. Braking distance is determined by vehicle mass and stopping friction.

There are a few issues here:

1) The car is less controllable in neutral. Do this, take a corner at a decent speed in 2nd or 3rd gear (depending on speed.) Now go around and do it again except this time push the clutch in before entering the turn. Tell me which feels more controllable.

2) Braking distance will be less with the engine braking aiding you. This is especially true if you downshift to an appropriate gear (so you are gaining very little speed.)

3) Most people (read: all automatics) allow their speed to climb up and then brake (repeating this process.) Instead of maintaining a set speed they let it get, say, 25% above the limit and then brake. Being at a higher speed, in neutral, while going downhill signifigantly lengthens your stopping distance. And this is to say nothing about the potential of overheating your brakes (when you may need them the most.) I used to go down a long, fairly steep hill every day. I could downshift into fourth and maintain the speed limit (45mph) without touching the brakes. Nearly every car behind me (statistically most automatics) would creep up and tailgate me because of this behavior.

For me this really comes down to good driving practice and being aware of your surroundings. Why would you want to have less control of your car, burn more gas with longer stopping distances?

 

[beaty]

Yes, above about 1500rpms with the car in gear, and the throttle closed, the injectors are shut off. To me the whole coasting in neutral thing is just juvenile but if you're doing it to appease the neighbors than go for it.

So say if I am driving on a highway at 60 MPH in 5th (3,200 rpm) and as soon as I let go of the gas, according to what you said I will be coasting without using any fuel at all? No fuel, no sparks, no combustion?

 

[ME]

Just the fuel is shut off, I don't think there's any easy way to shut the spark off (but I could be wrong.)

 

[SkyMan]

hmmm i always put the clutch in when going around corners.. .and then gradually let off the clutch when im back on a straight...hope that isn't bad.

 

[brendon2k]

I was talking about leaving the car in gear (foot off clutch) while you coast down the hill, in that case you're burning no fuel because the injectors are turned completely off. If you're in neutral the engine is actually above idle (depends on vehicle speed) and so you're burning fuel.



There are a few issues here:

1) The car is less controllable in neutral. Do this, take a corner at a decent speed in 2nd or 3rd gear (depending on speed.) Now go around and do it again except this time push the clutch in before entering the turn. Tell me which feels more controllable.

2) Braking distance will be less with the engine braking aiding you. This is especially true if you downshift to an appropriate gear (so you are gaining very little speed.)

3) Most people (read: all automatics) allow their speed to climb up and then brake (repeating this process.) Instead of maintaining a set speed they let it get, say, 25% above the limit and then brake. Being at a higher speed, in neutral, while going downhill signifigantly lengthens your stopping distance. And this is to say nothing about the potential of overheating your brakes (when you may need them the most.) I used to go down a long, fairly steep hill every day. I could downshift into fourth and maintain the speed limit (45mph) without touching the brakes. Nearly every car behind me (statistically most automatics) would creep up and tailgate me because of this behavior.

For me this really comes down to good driving practice and being aware of your surroundings. Why would you want to have less control of your car, burn more gas with longer stopping distances?

You are right about the fuel. On my way home there is a slight hill. I stay at the speed limit coasting or I slow down when I leave it in gear and have to use the gas. It takes power to make the engine spin and you would better milage by going neutral. If the car will go the speed you want in gear with out gas then you are just saving your brakes.

To you points

1) Explain the logic? People probably feel in more control because they can speed up.

2) Braking distance will only be helped if the brakes and not able to work well. Try letting just the engine bring you to a stop. It will take a long time the engine doesn't slow you down the fast. The brakes should be able to lock the tires from most speeds that you travel on surface streets as long as they can do that they do not need any assistance from the engine to make the car stop.

3)No one talked about riding the brakes while going down a mountain pass. Yes you are right about keeping it in a gear to keep you at a the speed you want to go. I have a lot of little hills and slopes where neutral keeps you at the speed limit though.

 

[ME]

First off I wanna say I think the gas issue is trivial, I only point it out so that people realize they aren't saving gas (they're using more.) The amount you would save is negligible. I mean maybe if you were driving back into Denver from skiing (all downhill) it would be signifigant but otherwise it isn't. But in that case the much bigger issue is brake fade. Stock braking systems start to fade pretty quickly. Imagine you've been riding the brakes the past thirty minutes and you need to panic stop.

1. Like I said, try what I suggested before. Take a turn at a decent clip in and out of gear. Tell me which feels more controllable. Cornering hard in neutral makes the car feel like a wet noodle, it just flubs through the turn.

2. I'm saying in a panic stop situation the car will stop shorter in gear with engine braking.

3. But if you leave the car in neutral it will build up speed and you'll have to apply the brakes. This will be greatly reduced if you leave it in gear. Obviously small hills aren't an issue. My whole point is if you put it in neutral to save gas, don't, because you aren't.

 

[ME]

hmmm i always put the clutch in when going around corners.. .and then gradually let off the clutch when im back on a straight...hope that isn't bad.

If you're taking the turns at relatively low speed it's not a problem. The point I was trying to illustrate is having to swerve at higher speeds. When the car is closer to its limit having it in gear is important.