Quote:
Originally Posted by meanjoe75fan
It seems this is a largely theoretical discussion, in that you're discussing the optimal means of descending a hill in which:
1. The slope is gentle enough that the PSL (or other maximum speed determined by driver) won't be exceeded by gravity.
2. Hill.has no steep curves/switchbacks.
3. Hill has no traffic-control devices at bottom that would make momentum conservation moot.
4. Vehicle is equipped w/ DFCO and is observed to engage for the lenght of the hill.
So YES, in this very special case of a "perfect" hill, coast in neutral. For most "real-world" hills, leave it in gear (DFCO) and get less fuel burn, "free" alternator and accessories, less brake-pad wear, etc.
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I think you're looking at it backwards. Don't look for the perfect place TO coast, look for the special cases where you should NOT coast. In other words, make coasting your default, and break that only when necessary (like the cases you mention above).
1. Except for long / steep downhills, just start the coast at lower speed so as to not exceed the speed limit.
2. Again, start slow at the top, and use engine braking to control speed. Try to fit some neutral in between the curves if possible.
3. Again, start slow. If it's a STOP, DFCO. If it's a light, DFCO just enough to hit it on green.
4. If you don't have DFCO, why are we even talking about this? Neutral!