Prodrive creates the P2 sports car

ATD uses data from wheel speed sensors (which can be shared with the antilock braking system), a yaw rate sensor and a steering wheel angle sensor to compare what the driver is requesting with what the vehicle is providing. If the driver is accelerating, or has some throttle applied, a torque can be applied to the appropriate wheel to counter oversteer or understeer. If they are braking, or off throttle, the system can be integrated with a conventional stability programme and brake the opposite wheel to enhance directional stability while reducing vehicle speed.

On P2, which is all wheel drive, the ATD system uses an active centre and active rear differential to modulate torque between the front and rear axles as well across the rear axle. Where appropriate, this allows the vehicle to enter a corner with the favourable dynamics of a rear-wheel drive car to minimise power understeer, then progressively increase torque to the front wheels as it moves around the corner. As the vehicle leaves the corner, the torque split can be biased towards the front wheels to provide maximum straightening force to help correct any oversteer or, alternatively, to help induce a powered drift.

With the active rear differential, P2 can also be given additional high speed stability for example in the event of an emergency lane change manoeuvre. By electronically controlling the lock on the rear differential, the car is provided with the agility to steer around an obstacle but then given added stability to help stop it spinning while returning to its path.

Harty says that the system has significant benefits compared with conventional brake-based stability programmes: "ATD is extremely responsive. It can predict the vehicle’s reaction to changes before it calculates the correction required, so can achieve the required wheel speed in around 70ms. Because it applies positive torque, working with the movement of the car, it also feels more natural, particularly to performance-orientated drivers. A brake-based stability system can not distinguish when a driver is deliberately pushing a car to its limits and when a driver really is in trouble. As a result, it has to always assume the driver is in trouble and so intervenes when driving hard so ruining the driving experience."

In addition to P2, Prodrive has two dedicated ATD demonstrators: an all wheel drive system, similar to the P2’s, on a Subaru Impreza and a front wheel drive system fitted to a Ford Focus RS which helps correct torque steer.

Exterior and interior styling

P2’s exterior and interior styling were created by Peter Stevens, who has worked with Prodrive on numerous road car and motorsport projects. His team produced a full scale clay model of the car to develop the styling and from this P2’s composite body panels were formed.

The P2 chassis was originally based on a Subaru R1 (a four seat mini car), which was completely reengineered to give P2 its coupe styling and to accommodate the new engine and drivetrain.

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