A couple more tips:
Try to put as much space between the subject (the car) and the green screen as you can. This helps to prevent shadows from the subject and the lighting for the car from creating any hot spots on the green. This basically means having a bigger greenscreen, which isn't always possible, but with something as small as a toy car it should be easier.
If you have access to a waveform monitor, definitely use it. It's much more helpful than a light meter. You want the screen's lighting to be as flat and even in brightness as possible.
Be careful about spill from the background. If light reflects off the green and onto the subject, then you'll have portions of the car that end up green too. This especially tricky with something shiny like a window or metal.
Personally, I think shooting the car moving would be difficult, as you'd need a lot more green screen area for the bigger background. Maybe move or zoom the camera instead?
Also, if you wanted to superimpose yourself driving it in the seat, you'd need a way to mask out part of the interior of the car too! That gets complicated.