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The best strategy I have seen in hills. This is assuming the hills do not exceed the grade threshold where you can not coast downhill without exceeding the speed limit to the point where you are risking a ticket, or seriously aggravating the drivers around you.
It's much like a roller coaster which can negotiate several hills on inertia alone.
Powering uphill you have the opportunity to use your engines best BSFC to add inertia to the vehicle. Highest gear that allows 80% of max load gives you the most power for the least energy, at about twice the typical average efficiency.
While that consumes more energy than just driving normally on flat ground, it more than makes up for the additional consumption by increasing your energy stored in the mass of the vehicle as you increase its altitude.
Then go engine off on the downhill coast and you recover that stored energy as speed maintained without fuel consumed.
The best tactic is to determine the speed you need to crest the hill, to reach the bottom with your desired highest rate of speed (without risk) and to let that peak speed carry you uphill as far as practical. Then you apply your maximum efficiency pulse to repeat the process reaching the peak of the next hill at the ideal speed to reach your maximum speed at the bottom of hill #2.
When the hills are the perfect grade, one which allows you to stay close to the same average speed at any point, either going uphill, or downhill, then you do not lose energy to aerodynamics at higher peak speeds at an exponential rate.
Hills slightly less steep than the ideal grade require some speed variation below your average, while hills above the ideal grade require higher speeds at the bottom.
Another thing you can do when the hills are greater than the ideal grade is to use accessory loads to lower your peak downhill speed. Things like AC (if its really hot) and alternator (if you can control its cycling) can be used to reduce your peak downhill speed to an acceptable level. While that is less efficient that not using them, its more efficient than having to change your strategy and get a ticket or ticking off everyone around you.
regards
Mech
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