first i think the background is off... ( my advice)
anyway look good ,
- the lamp is very sharp
- the front with the audi logo is very light and sharp too
side reflections : try too fond some donor(if you wan with graffiti :
http://auliaparama.com/wp-content/uploads/2013/03/blue-nissan-skyline-wallpaperdownload-wallpaper-nissan-skyline-blue-graffiti-free-desktop-y2gxucek.jpg
http://www.wallpaper4me.com/images/wallpapers/graffiti_burnout_w1.jpeg
http://www.wallsave.com/wallpapers/1920x1200/twitter-backgrounds/808263/twitter-backgrounds-graffiti-background-free-808263.jpg
keep it up