Why don't we have flying cars yet? People have been dreaming about the concept for a long time now, but it turns out there are some pretty good reasons.
Plenty of wealthy people have tried over the years, but air vehicles and land vehicles have some very fundamental requirements that don't mix well. All the designs so far end up being bad airplanes AND bad cars. A hybrid that is strong enough to handle wear and tear of road travel becomes too heavy to be a good flyer. A fair number of experimental pilots have wound up dead over the years for just this reason. Even driving short distances on roads would beat a typical airframe to bits; once strengthened it could barely take off. Normal aircraft wheels are too small and light to handle sustained highway driving, and offer minimal shock absorption. A typical car wheel is much too heavy for useful flying and the stress from landing would soon destroy them.For example, a Cessna 172 weighs around 1700 lbs., but adding folding wings and a road-worthy suspension would likely make it 2500 lbs. or more. And aircraft maintenance and repair is very expensive, so any of the normal, minor repairs that cars require would become unpractical, unless you are an aviation mechanic.
Some cool concepts are floating around out there to be sure, based on super-light carbon fiber, but on the road these materials would not hold up very well. Even a simple ding that vehicles sustain all the time would turn into a huge problem for airworthiness, and minor issues that can be overlooked for months or years on your Toyota could lead to catastrophic failures in the air. Though materials will certainly continue to improve, the inherent compromises will probably still exist.
Point to point aerial transportation will likely become more of a reality via VTOL (vertical take-off and landing)aircraft capable of landing in constrained areas, but it is unlikely you will be able to just fly to another town or state and then just drive it to the store to pick up some snacks. And even these vehicles require designated landing areas - landing one of these craft in a typical backyard or driveway would cause significant property damage and safety hazards, due to the high amounts of air pressure needed to keep the craft in the air.
Terrafugia Flying Car.
Road capable aircraft DO exist, but they make for lousy cars, and even worse airplanes. The compromises necessary will likely keep such vehicles from widespread use. That is, unless we figure out anti-gravity (a la Ed Leedskalnin/ Coral Castle) but that is a different subject entirely!