Flying cars are a bad idea at their core, the only technology that can make them work would be highly speculative 'anti-gravity' types of sci-fi. In the real world a flying object, that isn't lighter than the surrounding air, fails deadly.
Many people can barely control a vehicle in 2D. I'd hate to think how they'd perform with a third dimension added.
> No one has made a vehicle capable of driving and flying with equal ability.