In a nutshell, a well-known journalist and experienced historic racer was doing some track laps in a borrowed Porsche 917 replica, for a magazine article. While on track, he missed a gear and momentarily over-revved the engine. Bang, £40,000+ repair bill at a Porsche specialists. Racing flat-12s ain't cheap to fix

Although there was a "if you bend it, you mend it" agreement, the journalist says he complained to the mechanic during the session (before the engine blew) about a dodgy gear linkage. The mechanic said not to worry, and sent him out again.
The argument went to court, the journalist lost and now has to pay for the repair, plus costs, plus legal fees: over £110,000 UK ($175,000 US). Ouch.
Although the session was insured against a crash, like a conventional motor policy, the cover doesn't extend to mechanical damage.
http://www.telegraph.co.uk/motoring/mot ... rvive.html