One problem related to engine has been reported for the 1999 Jaguar XK8. The most recently reported issues are listed below.
My low (20,000) mileage but out-of-warranty car unexpectedly (no warning what so ever) threw its timing chain, resulting in damage to the chain and more importantly, to the engine. A damaged engine will cost more than $10,000 to replace. Based on web research, its a not-uncommon problem (with the timing chain) that other owners of this vehicle have suffered, regardless of service and maintenance, which the company refuses to acknowledge and address. The manufacturer has service advises that recognize the problem but still they refuse to take responsibility beyond standard warranty.