car. A number of small design changes for the body were tested in the wind tunnel; the final version had a drag coefficient of with downforce of at . The XJ220 was one of the first road cars to intentionally use underbody airflow and the venturi effect to generate downforce. Additionally, the XJ220 could be ordered with optional BBS wheels for improved brake ventilation and aesthetics. The rear lights used on the production XJ220 were sourced from the Rover 200. Chassis The production model utilised the same Alcan bonded honeycomb aluminium structure vehicle technology (ASVT) as the concept car for the chassis. The chassis design featured two box section rails which acted as the suspension mounting points and would provide an energy absorbing structure in the event of a frontal impact; these were successfully tested at speeds up to . An integral roll cage formed part of the chassis and monocoque, providing additional structural rigidity for the car and allowing the XJ220 to easily pass stringent crash testing. The rear-wheel steering was dropped from the production car to save weight and reduce complexity, as was the height adjustable suspension and active aerodynamic technology. The suspension fitted to the production model consisted of front and rear independent suspension, double unequal length wishbones, inboard coil springs and anti-roll bars, with Bilstein gas-filled dampers. The braking system was designed by AP Racing and featured ventilated and cross-drilled discs of diameter at the front and diameter at the rear. The calipers were four-piston aluminium units. JaguarSport designed the handbrake, which has separate calipers acting on the rear brake discs. Feedback from enthusiasts and racing drivers resulted in the decision to drop the anti-lock braking system from the production car. The braking system was installed without a servo, but a number of owners found the brakes to be difficult to operate when cold and subsequently requested a servo to be fitted. A rack and pinion steering was fitted, with 2.5 turns lock to lock; the steering had power assistance. The Bridgestone Expedia S.01 asymmetric uni-directional tyres were specially developed for the XJ220. Rally alloy wheel specialists Speedline Corse designed the alloy wheels, these are both wider and have a larger diameter on the rear wheels; wheels are fitted to the front and are fitted at the rear, with 255/55 ZR17 tyres at the front and 345/35 ZR18 tyres at the rear. Interior The interior was