Lol @ Gan. "Yeah."
There have been other forum posts about it, and an engine made in Flash supports it (the quick box2d one I think).
Anyways, you can try making a rectangle as the car body, then four rectangles on each edge connected via a revolute joint. Then allow the left and right arrows to rotate the two front wheels. Have the wheels control the actual velocity, and the car just goes along with the ride.
My guess is you'd have to modify the linear velocity every time you change the wheel rotation, and have some formula to calculate where the velocity should be going based on the wheels.
EDIT: Here it is:
Check out the car physics in QuickB2 (http://quickb2.dougkoellmer.com/bin/qb2DemoReel.swf
). They might suit your purposes. Source is at http://code.google.com/p/quickb2/