Most of what we have here is thanks to government and spoiled consumers allied. Crash standards made the cars big, luxuries like soundproofing, power everything made them heavy. Hybrids could be better if they were Geo metro weight class. Trucks could be affordable if they were just trucks.
I would like some niche regulations, maybe allow a "rural" truck type class, eased CAFE standards, no airbags, crank windows, simple bodywork. About a 1980s Nissan type affair. Same for city people, the smart cars are idiotic for the real world, but in the urban jungle do fine. Make them simpler and cheaper. No airbags, minimum creature comforts, light, small, and fuel efficient. Come up with some mixed use scheme that much like tractors neither class is allowed on the interstate, keeps them local to their target market.