Engine On Coasting

[actwithclarity]

If you're coasting down hill and have to stop relatively near the bottom, it's better to be in gear than in neutral?

For the sake of preserving as much momentum as possible, but not using neutral, would it be better to be in a higher or lower gear?

[Kodak]

Keep it in gear. Most engines will totally cut fuel above a certain rpm. As long as you can make it all the way to the stop sign (overcoming the engine braking) keep it in gear.

Higher or lower gear? Well, hard to say. Depends on the speed. You'd have to know what rpm your engine enters fuel cut-off. Naturally, no need to go too low and rev your engine real high.

There are at least a few metro owners around here, so I'm sure someone can advise you more specifically on what gear to use. Post your approximate speed for the hill.

Gotta hate those bottom-of-the-hill stop signs!

[euromodder]

Originally Posted by actwithclarity

If you're coasting down hill and have to stop relatively near the bottom, it's better to be in gear than in neutral?

Keep it in gear when you have to slow down or to control speed downhill.


Letting go of the throttle while staying in gear is a braking technique.
Braking is wasting energy.
You can always go further by not braking.
The engine may cut the fuel flow (DFCO), giving good instant mileage, but you'll be worse off in the longer run as you've been longer on the gas.

So, DFCO is LESS efficient than coasting, even with the engine on.
In the real world, combine both tricks depending on the need to control speed.

If it's safe and convenient to do so, start the downhill leg slower by slowing down uphill, going over the crest at the optimum speed, and (at least partially) coast down.

On a regular route, try to find the minimal speed that puts you at a good speed at the next transition point (crossing, stop, ...)

For the sake of preserving as much momentum as possible, but not using neutral, would it be better to be in a higher or lower gear?

The higher gear won't slow you down as much, so use that - if the engine can still make enough rpm to stay in DFCO.

[actwithclarity]

Thanks for confirming that euromodder.

In my case braking at the bottom of the hill is absolutely necessary, so I will continue to coast down in gear so I'm at least not burning any fuel (assuming I'm geared properly), which I would be if I was in neutral.

[Minibear453]

Just wondering, what happens in the older vehicles without the gas cutoff?

[Quazar]

My rule of thumb is out of gear coasting is best, unless you know for sure you have to stop.

Coasting not only allows you to travel farther, but decreases your rate of acceleration as you slow down, which I find is less aggrivating to other drivers.

Now if I have to stop, or know that Ill be in 3rd or lower to gain momentium, I select the gear that will get me there and gear coast.

[Kodak]

Originally Posted by euromodder

On a regular route, try to find the minimal speed that puts you at a good speed at the next transition point (crossing, stop, ...)

Euromodder brings up a good point. I'm not sure how steep or long your hill is, but I can think of one on my normal route that I now handle differently. Now that I peak it at a slightly [~5-7mph] slower speed, I'm much better off. Naturally, the amount of speed you can bleed off going uphill will be determined by whether or not there is a driver behind you.

[Arragonis]

Originally Posted by Minibear453

Just wondering, what happens in the older vehicles without the gas cutoff?

I believe it will still use the idle circuit to keep things going, however I'm not clear on in vs out of gear.

It could use idle x engine in gear rpm so be using more fuel in gear than just idle x idle rpm fuel out of gear.

[actwithclarity]

If I start rolling at the top, I will be up to 60km/hr by the time I have to stop at the bottom. It's sad because I have to drive UP that hill every time I go the opposite direction. :P

[euromodder]

Originally Posted by actwithclarity

If I start rolling at the top, I will be up to 60km/hr by the time I have to stop at the bottom.

Is that starting to roll from a stand still ?
If so, you'll have no option but to use engine braking rolling down.
If not, try to further reduce your speed going over the crest.

It's sad because I have to drive UP that hill every time I go the opposite direction. :P

Yeah, hills have a nasty side to them