1) background - looks good, has nice atmosphere,
2) front bumper - I really like Your idea for it but in few places has bad quality,
3) wheels - looks good, in good quality too,
4) rear door - You remove handle, so how You open rear door?

5) front glass - You hange background but in front glass (passenger place) you should make it more brighter or something, baceuse now isn't realistic
6) reflections - if You add car in new background, You should add more reflections for it.
Good idea for tuning. Little mistakes, I'm not sure perspective car on background is good.
7/10