Here in the UK we have the Unfair Contract terms Act which would apply. Any car in the custody or control of a garage, body shop or anyone who works for the motor trade has the liability for anything that happens to the car including poor workmanship. It's happened to a friend of mine, the workshop took his Passat and reversed into another car. They tried the same thing saying it wasn't their fault and advised my friend to claim off his own insurance.
However, here in the U.K. insurance law means that you have to give permission for the vehicle to be driven on the public road, therefore he sued them for unlawful taking of a motor vehicle as he did not consent for a test drive on the public road. Within 15minutes of sending the email he received a phone call offering full costs and compensation. The disclaimer wasn't worth the paper it was written on.
