It would be more blocko if you used black25, black50, black75, and whiteCheck for the interior and maybe just a few grey/black bits. But it is all up to you.
Also, I'd probably make the windscreen angled from the side.
Red line shows how usually people make the pillars on their cars. This is the thing which really irks me about most user-made cars.
Green line is how the windows slope on the sides.