Sweetsixteen
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- Jul 7, 2014
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Picking up on JR's point, I have experimented with closed throttle going downhill (useful if you need to scrub off speed), and coasting in neutral. As an alternative. I have found that the latter gives considerably more mpg in hilly country. It helps a lot if you know the roads, because you can then plan ahead as you drive.
The argument seems to rest on the 'fact' that many modern engines cut off the fuel supply on a closed throttle (and I query that, because I have been informed that this only applies above idle revs), while the engine has to keep burning fuel when you are coasting.
So here's a hypothesis:
If you calculate your top gear speed at idle revs (in one of my vehicles it corresponds exactly to 20mph) then as long as you are coasting in neutral above that speed you should be saving fuel. An added bonus is that you often reach the base of the next incline with more momentum, which gives you greater initial speed attacking the incline.
The argument seems to rest on the 'fact' that many modern engines cut off the fuel supply on a closed throttle (and I query that, because I have been informed that this only applies above idle revs), while the engine has to keep burning fuel when you are coasting.
So here's a hypothesis:
If you calculate your top gear speed at idle revs (in one of my vehicles it corresponds exactly to 20mph) then as long as you are coasting in neutral above that speed you should be saving fuel. An added bonus is that you often reach the base of the next incline with more momentum, which gives you greater initial speed attacking the incline.