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[Closed] Which uses the least fuel, going downhill in gear or in neutral?

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Oh, that seems obvious now.
Cheers!


 
Posted : 18/02/2015 6:57 pm
 sbob
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molgrips - Member

Cruise control doesn't apply the brakes or change gear for you - just modulates the throttle.

Wrong on both counts for modern autos with adaptive cruise.


 
Posted : 18/02/2015 8:22 pm
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Sui - Member
If the car has active braking...My manual 5 series has it, and will break on downhills

That must get annoying after once or twice!


 
Posted : 18/02/2015 8:31 pm
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It's more economical to (1) go downhill in neutral, foot off the gas than (2)in gear foot off the gas.
Look at the rev counter... (1) approx 850rpm compared to whatever it is when your in gear using the engine...


 
Posted : 18/02/2015 8:34 pm
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Wrong on both counts for modern autos with adaptive cruise.

Ok adaptive cruise maybe, but with normal cruise it's far from universal even on modern cars.

(1) approx 850rpm compared to whatever it is when your in gear using the engine...

Well the point of the thread is that even though the engine is doin 2krpm there's no fuel being injected into it...


 
Posted : 18/02/2015 8:43 pm
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What sort of fuel are you running...?

I think it makes a difference if it's liquefied dinosaur based


 
Posted : 18/02/2015 8:57 pm
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Haven't got adaptive cruise on mine, just the normal cruise but whilst on cruise on downhills it will apply the braking to keep the speed constant. That is due to there being no engine braking at all on my car, it has a CVT gearbox and regenerative braking. So going downhill in gear not only uses less or no fuel depending on the incline but also charges the dirty great big battery located below the back seats, thereby increasing the range. Pulse and coast works great for upping the MPG.


 
Posted : 18/02/2015 9:09 pm
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[i] My manual 5 series has it, and will break on downhills[/i]

I thought German cars were reliable.


 
Posted : 18/02/2015 9:28 pm
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"Look at the rev counter... (1) approx 850rpm compared to whatever it is when your in gear using the engine... "

Uh huh


 
Posted : 18/02/2015 9:37 pm
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Not explicitly illegal to coast however it is frowned upon in the highway code.

Definitely an infinitely worse idea to switch the engine off altogether.


 
Posted : 19/02/2015 4:13 am
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