Thanks 13_gecko_rubi, it's nice to hear from someone with actual experience.
The only way to really know about the off-road range would be to build something and test it in a variety of conditions. I'm sure the efficiency would be a lot better on White Rim than Pritchett Canyon, for example. But even if we take your 50% number that's 150 or 160 miles for the big battery.
But where does all the energy go? On the highway it goes mostly to aerodynamic losses. That's not going to be much of a factor off-road. Or should I read your use of "event" as meaning "race"? EVs suck at racing (except for drag racing
The motors are much less efficient at high output. I guess sometimes on "ordinary" off-road trails (eg Hell's Revenge) one uses a lot of power for a few seconds for climbing a big hill. But I wouldn't think that would be as big a factor as the reduced aero loss. Maybe it's going to heating up the tires and shocks? That's certainly much worse off-road, especially when aired down. But that much?
I didn't understand your point about regen (unless you meant racing). It might be that the regen system would need to be designed to provide more force than Tesla's so that more energy could be recovered in steep down slopes, especially short ones. But that's easy enough. The reason Tesla doesn't do that already is that it would "fell funny" to have that much "engine braking" especially for folks used to ordinary automatic transmissions. Tesla even has an option to make the regen LESS powerful but, sadly, not one to make it more so. If I were designing it, I wouldn't have any mechanical brakes at all (if I could get past the safety regulations).
Did you actually build an electric Hummer? Sounds interesting.
Yeah, a range extender is a pretty good idea. But it's a huge amount of additional complexity. I would rather just have a bigger battery, if the cost wasn't too outrageous. Maybe the extender could be made optional somehow?
I don't want to argue about Tesla's business plan. All I'll say is that a lot of smart people are investing a lot of money in Tesla and they're not doing it just to be nice.