The contact owns a 2011 Jaguar XJ. The contact stated while driving 75 MPH, the vehicle began to decelerate independently, prompting the contact to pull over to the shoulder of the roadway to have the vehicle towed. Several unknown warning lights were illuminated. The vehicle was towed to an independent mechanic, who diagnosed a failure with the engine. The contact was informed that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline for assistance. The failure mileage was 88,000.