Quote:
Originally Posted by hondaworkshop
I have 20 miles of rolling hills to drive... just about equal parts up or down with no stoplights.
I can:
1. Coast down each hill in Drive (my auto will decelerate going downhill but will use 0gph), then accelerate up the hills under a load
2. Coast down each hill in Neutral (my auto will not decelerate, but will burn idle fuel at about .25 gph), then accelerate up the hills under a load, but with a better entry speed...though the manual shifting of an automatic does worry me.
3. Accelerate moderately down hills with very little load, then coast up the next one as much as possible.
Thoughts?
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The SAE published two books on mpg years ago.One article dealt with the Chrysler team which entered the Shell Mileage Marathon,and how they dealt with hills.They pre-tested their car for best mpg per road grade.Then,during the test,they used a ball-bearing in the bottom of the ashtray as a crude inclinometer to tell the grade of the road,and then drive according to the pre-determined speed for highest economy They did allow the car to accelerate on downhills and then basically held a constant throttle position as the car lost speed on the uphill.They might let speeds fall to 50,40,30,or 20-mph,depending on grade.They never attempted to gain speed on an uphill reach,avoided moving the throttle as much as possible.I favor letting gravity help accelerate on downhills,although the highway patrol watches that sort of thing.Be careful.I've enjoyed good results driving a constant throttle setting,letting the speed rise and fall as it may.I understand that some automatic transmissions will burn up if coasted,however that may only be true for an "engine-off" scenario,where the pump is not turning.Don't know,be careful.as you know,trannies are very expensive!The other thing is that if there is only one lane in my direction,I'll drive the posted speed limit if there is traffic around.If the highway is empty,I'll take liberties with speed.Impeding following traffic,which is moving at the speed limit wastes the other guy's fuel and makes for hard feelings.I won't do it.