The Quadra inherits the 4wd system first used in the Espace. Engine torque is split, via a centre differential, 65 per cent to the front wheels and 35 to the rear under optimum conditions. A viscous coupling senses any slippage between the front and rear wheels and transfers drive to those which have the most grip according to need. If conditions get really slippery, the driver can opt to pneumatically lock the rear differential, but then only first and reverse gears can be engaged. Also, with the diff lock engaged, the anti-lock braking system is switched out.