If you were going for a toy look, you nailed it.
But if you were going for a realistic or plausible
interpretation of a car design, then I think there
is still much detail to be put in.
For starters, the vehicle is too round and like Sly
said, it looks like marshmallow. Also, putting in
some texturing would give it a more realistic view,
especially on the tires which look like just the
inner tube with rims.