What if anything does the "R" on the rear of my XF stand for?????????

 

"Race". I would be surprised though as Jaguar didn't launch the "R" version of the XF until the 2010MY. If it really is an XFR you should have the letter "R" embossed on the front seat head restraints, on the vertical spoke of the steering wheel, and on the dashboard trim in front of the passenger. If you don't have those identifiers then someone has just glued the "R" badge to the rear of your car.