I've seen a number of electric assisted bikes, some were posted in the
bike thread. Makers have taken various approaches, some for power, figuring you only need help on big hills, some for efficiency, figuring range was the priority, some for cost, for obvious reasons. Agnelli's bikes are dedicated to retro art foremost, and the fit/finish is exquisite, which tells me they are very expensive too, although I haven't seen any prices.