wheel arch 
noun
An arch-shaped cavity in the body of a vehicle, which houses a wheel.You could put up a deckchair and sunbathe in the space between the top of the wheel and the wheel arch....
- The damage is from the front wheel arch all along the car to the back wheel arch, nicely dented, scratched and gouged.
- The black paintwork of this car was in very good condition, the only marks being a small scuff on the rear bumper plus a slight dent on the off side rear wheel arch.