Quote:
Originally Posted by esnap
It would seem that you are typically going to be staying in lower gears while pulsing/burning up a hill where you can quickly gain speed and get into higher gears while pulsing down a hill.
It is my contention that the car is more efficient gaining speed in a higher gear while going down hill thus storing inertia for the coming hill climb.
Here on the big island we will drive from Hilo to Kailua-Kona over Saddle road but in that case you have to just get up that mountain getting poor mileage but then you get to coast for miles and mile on the other side.
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The method you describe is not correct for most situations. You want to hold the highest gear possible that allows you to travel at a reasonable speed up the hill. This might mean pressing the throttle about 80%. It is more efficient than downshifting and using less throttle opening. Coast the downhill portion and supply some pulses if the grade isn't steep enough to maintain the speed you want. Much easier to do with a manual transmission.
Going over a mountain pass is very efficient since it acts like a long pulse and glide. You pulse up the mountain, and glide down the backside. I did this recently going from Montana to Oregon through some passes. My car is geared low, so I could hold 65mph in 6th gear going up, and then neutral coast on the backside. If only I had an engine kill switch, my economy would have been even better.