The M5's reinforced active locking and torque-vectoring reardifferential (the Active M-Differential) brilliantly adjudicates traction between the rear wheels.
Both cars can be equipped with optional torque vectoring, a brake-based system built to augment the mechanically locking reardifferential and help put power to the ground.
Mathematical models are used to simulate the rest of the car, from the gearbox and reardifferential to the force exerted by the road, so that the engine is subjected to the same demands and forces as it would be in a real car.