Yeah, flying cars are "out there", inherently, and you have the air space thing to consider (thought that is amenable to control with computers I think).
The primary function of a wing is to covert drag into lift. To get a thing "up" requires energy, a lot of it. A car does have some rolling resistance and wind drag of course.
But as you say, the only part of that related to "lift" is meant to generate downforce, antilift.
Cars with a lot of downforce have a lower top speed than the same car with fewer "wings" on them (spoilers etc.).