Some musings on future power trains

I have a hybrid Rav4 now, it averages 44mpgs compared to my older CRV that averages 23 mpg. One thing that is not often mentioned when comparing pure EV to hybrids is the cost of electricity. Where I live electric costs are $.22/kwh which is higher than most of the US. At $2/gal of gas it is cheaper to drive my hybrid than an EV or plugin hybrid. Having said that, when you try to scale that up to a small RV the mpg improvement over an ICE engine will go down. So if you compare the 3.5 ecoboost ICE to the hybrid in a F 150, the projected mpg is about a 20% improvement. With a TC or small TT you might see 1/2 or 10% improvement due to the increased weight but that may make a lot of sense, because when not towing, the truck can be used as your DD and you would recoup the added cost of the hybrid in several years of driving. I can also see it scaled up to a small Class C say 24 ft if you can do some weight reductions that Groover mentioned in his OP like eliminating the genset etc. Once you start eliminating things you not only eliminate the weight of those things but also the weight of the support structure. Just look at the weight of a DP compared to the same size gas MH, the gas MH will be 40% less weight. Smaller engines will have smaller transmissions and less supporting structure etc. I think a front wheel drive ICE with a rear wheel drive electric eng with a 180 in wheel base would also save weight and improve the ride quality. The electric engine would get it moving and the ICE eng would take over once it gets to max torque. This MH would do much better on mountainous roads out west due to regenerative braking than on straight highway driving. I don't know how much solar would add back to the batteries with flexible panels covering the MH. It would take a lot of engineering to scale this up to a DP weighting 30k lbs but I guess as batteries become more efficient and affordable it could happen but by then I would be out of the market.