If the definition of a flying car is a vehicle somebody gets into and uses it to leave the ground and fly through the air and land in another place, we already have them. They are called airplanes. Some of them are even small enough for just one or two people! So why don’t we think of them as flying cars? Because you need to fly them from an airport! And why do you need to fly them from an airport? Because you need a runway and you need air traffic control. You can build an airplane with foldable wings that you can drive on a highway if you want, but why would you? It would be vastly simpler and cheaper to land your airplane and rent a car-type car, which, you know, is designed to drive on roads without hauling folded wings around with you everywhere. To illustrate the point, you can buy a boat with wheels that you can drive on a highway, and how many of those do you see?