We had a "shop car" that had been a high mileage test car. It had about 65,000 miles on it when engineering gave it to us to play with. It had been wrecked 3 times, and had several clutch's put in it. (due mainly to inept drivers)
We put a new clutch in it, fixed most of the body damage, put on a prototype Borla muffler and newer tires, and used it to give guests rides around the plant. It had a few rattles and squeaks, but it ran perfect. I know of a few "unofficial" acceleration contests between it and new GT's, and it never was beaten.
Sadly, when the Wixom GT shop was closed , the car was sent to DST, Ford's official junk yard, to be sent to the big GT heaven in the sky. There was a lot of damp eyes that day.:thumbsup