Is that a SUV or a station? Also, can i make an overlay? :D
Edit: You should make an overlay too.
Try to improve these, for start:
1st - Make the wheelbase longer. (It must fit at least 3 wheels between, so, you draw 5 circles, side-by-side)
2nd - Make the floor line
3rd - Trace a line, crossing the wheels, to define the ride height.
4th - define the front and rear overhang. (This also defines your engine position, if it's like a BMW, it has a really short front overhang, but the cabin is more behind... pushing the doors more to the back) Yours is more like an Audi, with the engine really up front, so the front overhang is bigger. Rear overhangs are longer in stations and sedans.
5th - to give it more of a 3d feeling, draw a line, under the car, simulating the wheels from the other side.
6th - Look for side view references on internet.
This shows the wheels on the other side quite well.