Originally Posted by KRL

The ideal system would be one where an air car could just use a computer controlled anti-gravity energy field system.

In concept its really not very complex. All you need to do is find a charged particle mechanism to exert its own gravitational field to counteract the gravity field of the earth around the car and you'd be airborne instantly with minimal thrust which could be ion based like they use on the space probes.

You can read the theory behind this on this link:

http://suzuki-t.hp.infoseek.co.jp/pdf/bbe.pdf