I see on some post the numbers XKR 75 or 100 or 150. What do these numbers represent. Thanks

 

The early XK8/XKR's 1996-2006 were designated X100 by Jaguar and the newer XK/XKR's 2006 on were designated X150.
All the other models have similar designations.

 

XKR75 was the 75th anniversary edition (75 years of Jaguar).

XKR175 was released at the same time for North America, slightly different model.

XKR60 was 60th anniversary of the XK120

XKR100 was to celebrate William Lyons centenary

There have been a number of other special edition XK's