About 30 years ago I spoke to a bloke in Christchanurch (NZ) about his mobility scooter. He told me that he had built it himself. It had 4 motors, one in each hub, four large deep cycle batteries, and a generator powered by a Honda 4 stroke engine for recharging while mobile, this also put the voltage up. On battery alone it would do about 20kph in top gear, and 10 in low gear. In top with the generator running it ran at 25 kph(all illeagal). He lived in an outer suberb, and used high power in unpopulated areas.
Ian S C