 For the M1's exterior, simple modifications were made to adapt the car aerodynamically. A deep spoiler was added under the nose of the car, while an adjustable wing was added on two mounts at the rear of the engine cover. The arches for the wheels were extended outward to shroud the wider 28 centimetres (11 in) wheels in the front, and 32 cm (12.6 in) wheels at the rear. The alloy wheels, designed by Campagnolo, featured a central locking nut and mimicked the straked design of the production car's wheels. Inside, the car featured no finishing or luxuries from the road car, only a rollcage for driver protection. The glass windows were replaced with clear plastic.
