It happens all the time. When I worked at Mercedes, I was in view of the service area and saw every single car the techs took out to give a test drive after finishing work. When the AMGs and such were done... you knew it without seeing it because you'd hear them peel out and haul ass down the side streets. Sometimes in modded cars or exotics like the SLS, Black Series models, SLR, etc they'd fill the cars up with other techs to "assist in the test drive." The breaking shit part is pretty fucked, though. I've never seen that happen and when a timing belt snapped during a test drive the dealer and techs didn't try to hide it and blame it on just the owner (I know because the car owner is actually a family friend).
This happens at every dealership in every city, state, and country. That's why I like working on my shit myself.
Stop putting stuff like painted reflectors and premium package in your signature. You're embarrassing.