I've just been quoted £980 to fix the same problem - loud bang on the motorway and then 'restricted performance' in red. I think Jaguar need to take what is obviously a design fault seriously, particularly as they had amazing results in the JD Power survey saying that the XF was really reliable. This is a shocking way to treat customers, and will inevitably result in people thinking twice about buying a car that has a built-in liability to blow. The car has done 52000 miles and was bought new - probably won't buy a Jag again. Shame.