scottm;931694... to slow down less on declines and use the momentum instead to help up the inclines said:
It would be helpful in putting this question to rest if someone sufficiently motivated were to do the test well and publish the results. However, my money is so firmly on high regen being better that I am unlikely to spend the time on it.
The reason I doubt that the test will be worthwhile is simple. Increasing speed increases air and rolling resistance energy losses, and that is energy that can never be recovered. Whereas, energy put in the battery can be recovered. It's a fair point that the extra speed is another way of storing the energy and will contribute toward the next hill climb. I guess if the energy lost to drag is less than the energy lost in regeneration, you could come out ahead with lower regen and higher speeds. But my suspicion is that drag goes up so fast with speed that this is unlikely to pay off in any real case.
Consider the extreme case of crossing the continental divide on I70. If you allow a Model S to roll freely down that incline, you will easily exceed 160 kph, threatening your ability to make the corners, not to mention increasing drag tremendously. If you use brakes, you'll be wasting even more energy. My suggestion is enable enough regen to limit your speed to the legal range, and enjoy the ride a lot more. In more marginal situations, the advantages may be, well, more marginal. But I'm keeping my bet on strong regeneration, especially in the mountains.
Afterthought: I would be interested in having regen strength adjustable over many levels, as in the Cadillac ELR. There may be a case for making it no stronger than needed to enforce legal speed for current conditions. But conditions can change and then it would be best to be able to strengthen it when one finds oneself gaining speed undesireably.
