PSM is an automatic control system for providing stability at the limits of dynamic driving performance, and is a standard feature of every 911. Sensors work continuously to monitor the driving direction, speed, yaw velocity and lateral acceleration of the car. 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 – recognisable by the flashing indicator light in the cockpit – 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. The control interventions are smooth and precise, giving an agile response. When ‘Sport’ mode is selected on the optional Sport Chrono Package Plus, 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 shortens the braking distance even further and the braking inputs are smooth and precise, thereby enhancing comfort.
An enhanced PSM system, now also available in rear-drive models, is characterised by two additional functions: the precharging of the brake system, and brake assist.
If the driver suddenly releases the accelerator pedal, the 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 – i.e. if the pressure on the brake pedal exceeds a predefined level – the brake assist function uses the PSM hydraulics to apply maximum brake pressure to all four wheels.
If you want a purely active driving experience, you always have the option to deactivate PSM. It is automatically reactivated, for your safety, only if either of the front wheels (in sport mode, both of the front wheels) requires ABS assistance. The ABD function, however, remains active at all times.
In conclusion, PSM offers a high level of driving stability and safety – and typical Porsche agility at the same time.