By the way, many Cessna 182s can take automobile fuel without problems.
The fact is, when flying an airplane, the act of flying itself (i.e. manipulating the controls to achieve flight) is the easiest thing to do. It's dealing with the weather that is the most dangerous part.
As for the ability to land anywhere, forget it. In the Philippines, for instance, you'll find very few roads without overhead powerlines and electric posts. You can't land on roads just like that without endangering yourself and other motorists.
As for parking in the garage, I know someone who used to have a Hughes 500 helicopter parked in the garage of his Maria Luisa home.
Perhaps we'll find that flying cars will simply be compromises, neither here nor there. They won't make for very good cars nor will they be very good planes.