Prius uses electric power-assisted rack-and-pinion steering that enables the system to operate when the petrol engine is not running. Compared with the previous car, the processing unit has been increased from 16 to 32-bit. The number of turns from lock-to-lock has also been reduced, from 4.0 to 3.6. The turning circle is 10.4 metres, which is acceptable for the wheelbase. On the i-Tech version, the steering is linked to the stability control system, which means it can act in concert with selective wheel-braking to control any wayward movement of the vehicle. The system varies power assistance according to the vehicle’s road speed.