Seems there are glitches with nearly every vehicle in the new Battlefield 2 Sandbox 1.0. Basically, there are two types of glitch you can do, and both involve floating while entering the vehicle. You can float, run toward, and enter the car to get it to glitch in one way or you can run, float, and enter the car at the same time to get it to take off into the air. It takes a little practice, but you'll get the hang of it.