either ZF makes the most efficient transmissions in the world or the HP/TQ ratings for Jaguar are very under rated

 

It's the adaptive programming in the transmission. The engine transmission combination can be very effective during real world driving.

 

The race drivers at the R Performance Academy will tell you that the XFR is faster in most circumstances with most drivers (but maybe they knew what I drove), but by any measurement their respective abilities are very close indeed. I can tell you from experience that the XFR is easier to drive at the limit than the XKR, which is twitchier and less progressive. The XFR I found easier to control on the throttle in very high speed cornering. That said, the XKR would be my weapon of choice for lower speed Autocross. That twitchiness makes it more manoeuvreable when you most need it. Sounds faster too!

 

Although I never got to drive the XKR around the track, the XFR was surprisingly "light on it's feet", if you will and it seemed easier to drive at the limit. So, I would agree with the race drivers as well but man do those XKR's make an great sound when you open them up.