You can download Audi on Road from here : https://play.google.com/store/apps/details?id=lamborghini.wallpapers.CarWallpapers.CarSounds There are more than 30 thousands car wallpapers and it is the best Audi wallpaper source.
Some popular Audi background categories in the app like
Audi A8 backgrounds
Audi Q2 backgrounds
Audi Q7 backgrounds
Car Wallpapers 