You are right...if we do it like coruscant did it. When your in the air, you have a whole new dimension to worry about, up and down. It confuses us. Just recently have planes started to use different altitudes than each other, as it was just easier to plan their routes accordingly on the same altitude. However, we don't all need to be at the same height. Their's quite alotta space up there. Plus, everyone would have their own route in the air, it doesnt make sense to have any air traffic jams. We would definitely need a computer/visual way of seeing everyone in every dimension around you, but I don't think collisions would be nearly as common as they are now. However, a collision in the air would be a cluster****As cool as the idea of a flying car would be, it's a horrible safety hazard. Think of Star Wars' Coruscant and it's traffic lanes. If you get in a crash, you fall hundreds of stories to your death. If you say, "but we'll just use a computer to manage the cars," you should know that a computer like that could be easily attacked or spammed with fake cars and crash, leading to lots of problems.
...would be no different than normal cars, except impossible to control and stop, and only be a few feet off the groundFlying cars are stupid, but hovering however..
*pictures Futurama*...would be no different than normal cars, except impossible to control and stop, and only be a few feet off the ground