I have never understood the thinking of people who want to make cars that fly. Of course, I understand the coolness of making a car fly, just not the desire to make a world where cars fly. We have enough problems with people who can't drive on the ground and now we want to fill the sky with them? That's just what we need, car wrecks raining down on us like meteorites!
I'm not totally rigid on this point though. I think there is a compromise to be had. Let's meet half way and let everyone have a personal blimp instead. They look like they would just bounce off each other if they collided.
The only thing left to do would be to confiscate all the slingshots from every kid in the world.