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Old 10-06-2014, 10:24 AM   #1 (permalink)
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Coast in gear or in neutral?

Hello,

As above do you coast in gear or in neutral?

Which is best?

I coast in gear as I heard on top gear clarkson said

"A modern engine uses no fuel coasting in gear"

Which is the best! I have never compared the two methods myself just always coasted in gear and now I'm doing it with the engine off where I can! Even better coasting!

Thanks for your advice

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Old 10-06-2014, 10:35 AM   #2 (permalink)
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Coast in neutral when you want to conserve your momentum.

Coast in gear when you have to sacrifice your momentum.

When forced to stop use downshifting to try to avoid stopping altogether if possible.

If you are going downhill and the grade allows you to maintain your target speed, use neutral and possibly enigne off. If the grade is too steep then use gears to slow down.

If you know the grade is too steep then slow down before you get to the top of the hill, before the downhill grade.

The only time I coast in gear is when I am approaching a red traffic light. My objective is to let the light turn green and go through the intersection with the least change in my target speed.

My car is an auto transmission, so no engine off coasting for me.

regards
mech
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Old 10-06-2014, 10:36 AM   #3 (permalink)
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That is dependent on your situation. If you can see the red light from far off, neutral would be better as you can coast a lot farther in neutral than in gear. I'm assuming you have a manual right? Because if so, you should probably install a kill-switch, then you can coast in neutral and burn no fuel.
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Old 10-06-2014, 12:02 PM   #4 (permalink)
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Thanks for your responses guys.

So when I know I will be stopping coast in gear and when I won't to keep going coast in neutral.

Which uses more fuel then in gear or in neutral?

Thanks
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Old 10-06-2014, 01:30 PM   #5 (permalink)
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I coast in gear as I heard on top gear clarkson said

"A modern engine uses no fuel coasting in gear"

of course it does......
an engine uses no fuel when it is turned off.
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Old 10-06-2014, 02:17 PM   #6 (permalink)
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Quote:
Originally Posted by mcrews View Post
I coast in gear as I heard on top gear clarkson said

"A modern engine uses no fuel coasting in gear"

of course it does......
an engine uses no fuel when it is turned off.
I think you are misunderstanding, many (most?) newer engines are calibrated to cut injection completely on deceleration. When it kicks back on depends on a whole slew of variables, engine rpm, engine temp, catalyst temp, gear selection, etc.

Hard to use any fuel if the injectors are not firing.
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Old 10-06-2014, 03:19 PM   #7 (permalink)
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Quote:
Originally Posted by adam728 View Post
Hard to use any fuel if the injectors are not firing.
If you're engine braking and bringing yourself closer to the point where you have to get back on the gas, you are using fuel. It just doesn't look like it at the moment.
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Transmission type Efficiency
Manual neutral engine off.100% @MPG <----- Fun Fact.
Manual 1:1 gear ratio .......98%
CVT belt ............................88%
Automatic .........................86%

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Old 10-06-2014, 03:46 PM   #8 (permalink)
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Quote:
Originally Posted by mada88 View Post

Which uses more fuel then in gear or in neutral?

Thanks
Coasting in neutral
uses a small amount of fuel as the engine idles, but you will coast much further than you will when engine braking (coasting in gear). Coasting in gear uses no fuel, but you will bleed off speed quicker, so you will need to press the accelerator and start using gas much sooner than you would if you were coasting in neutral. Coasting in gear is engine braking, which converts into heat the inertia you had previously burned fuel to build up, but it just does it at a slower rate than you typically do when using your friction brakes.

For most driving (from low to high in fuel usage); coasting in neutral (engine off), coasting in neutral (engine on), coasting in gear (DFCO). Use coasting in neutral (preferably with engine off) in most cases, only using coasting in gear when approaching a lower speed zone or stop or when going down a hill where coasting in neutral would allow your speed to get too high.
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Old 10-06-2014, 05:13 PM   #9 (permalink)
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Quote:
Originally Posted by Fat Charlie View Post
If you're engine braking and bringing yourself closer to the point where you have to get back on the gas, you are using fuel. It just doesn't look like it at the moment.
If injectors are not firing, and no fuel is being burned, how do you use fuel, but it doesnt look like it at the moment? Maybe you worded this differently than you meant it.


I do understand that engine off coasting in neutral is best as an overall efficiency sort of thing. My Mazda is a prime example, lift your foot off the gas at 55 and the short gearing engine brakes you to 35 (injectors off the whole time) in the same distance that it would coast down to only 47-48 mph or so in neutral. So I'll actually have to get back on the throttle to make it to the intersection on the way to work, using more gas than an engine off neutral coast would. But that still doesn't mean its burning fuel while coasting down.
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Old 10-06-2014, 06:18 PM   #10 (permalink)
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Quote:
Originally Posted by Xist View Post
I beg your pardon, kind sir, but perhaps did you intend to write "Coasting in neutral" in the first instance?
oops, I mean "neutral", not "in gear"

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