Four wheel drive
Most four-wheel-drive saloon cars on the market today started life with only two-wheel-drive, and have had four wheel drive added to increase traction and driveability. The two-wheel-drive version of the Audi Quattro shown here is a front-wheel drive model.
It is possible to add drive to the undriven wheels of most vehicles - whether they were originally front-wheel or rear-wheel drive. More and more manufacturers are now following this trend in response to customer demand.