PSM, which comes as standard, is an automatic control system that stabilises the vehicle at the limits of dynamic driving performance. Sensors continuously monitor driving direction, speed, yaw velocity and lateral acceleration. Using this information, PSM computes the actual direction of motion. If this direction deviates from the desired course, PSM initiates braking interventions targeted at individual wheels in order to stabilise the vehicle.
Under acceleration on wet or low-grip road surfaces, PSM improves traction using the ABD (automatic brake differential) and ASR (anti-slip regulation) functions, giving an agile response. When ‘Sport’ mode is selected on the optional Sport Chrono Packages, the PSM intervention threshold is raised to enable greater driver involvement – particularly at speeds of up to approximately 70 km/h (45 mph). The integrated ABS can further reduce the braking distance. For an even sportier drive, PSM can be deactivated. However, it is automatically reactivated for your safety if either of the front wheels (in ‘Sport’ mode, both of the front wheels) requires ABS assistance. ABD remains permanently active. PSM has been enhanced and now includes two additional functions: precharging of the brake system, and brake assist. If you suddenly release the accelerator pedal, PSM automatically readies the braking system. With the braking system having been precharged, the brake pads are already in light contact with the brake discs. Maximum braking power is therefore achieved much sooner. When sudden braking is detected, the brake assist function applies maximum brake pressure to all four wheels.