One problem related to mid/rear seats assembly has been reported for the 1998 Jaguar XK8. The most recently reported issues are listed below.
While driving at 45 mph drivers seat broke away from track putting me into the back seat causing temporary loss of control and running off side of road ripping front spoiler off car. Went into dealer who called Jaguar about problem. Mfg. Decline to pay for repairs stating car out of warranty.