I have a 2008 XJR with 56k miles. The other day, as I was pulling into a parking spot, the engine just shutoff. I put the transmission in park, turned the key counterclockwise to the off position, and was able to reststart the car and park it. I bought the car 11 years ago CPO at 17k miles from a Jag dealership. Over the years of ownership, I have kept up with maintenence and never had any problems with the car. The early engine shutoff while driving only happened once, but Im concerned it may happen again if I happen to be driving on the street or highway. I have no clue why this would happen and would like to know if this has happened to other Jaguars?

 

While parking I assume you were making some large steering inputs? I had some past experiences with my XJ stalling the engine while parallel parking. I could tell it was going to happen because the RPMs were fluctuating. It would only happen in very hot conditions. Unfortunately I'm not going to be much help because I never found an issue on my car, and it didn't happen consistently enough to diagnose thoroughly. My thought was the throttle body itself getting worn out (even though both your 08 and my 06 have the later design).

 

Could be a simple as a hose that flexed enough to create a vacuum leak such that the air/fuel was so weak the car stalled.