1= low wheels res, and bad positioning,
2= where is the exhaust, (that black hole in the rear bumper)
3= the selection aren't smudge,try to use anti-aliasing ,and 0,3=0,5 feather-radius when make selection
4=the interior look fake
5= the brush is ok ,it can be better
6= the lateral window is crooked
try with simple modifications of the car ,and be carefull of detail