The 2010 brochure has the curb weight listed at 3651 lbs for the XK & 3865 for the XKR. A difference of 214 lbs. The supercharger has a steel rotor & aluminum housing & the intercoolers are aluminum........so i cant really understand it. 60 lbs sounds reasonable..214 lbs is the weight of a large person. The 130 hp difference is probably only feels like 100hp difference with the weight factored in. 32% more hp...but an increase in weight of 6%. Where is the added weight coming from?

 

The specs for the 12 verts are as follows:

XK 3739 lbs
XKR 3968 lbs

The HP diff is 385 to 510 (125) but the torque also jumps from 380 @3500 rpm to 461@ just 2500, an extra 81 ft lbs at 1000 fewer rpm is huge.

Part of the extra weight is due to the intercoolers extra cooling liquid, I believe the R may also get a higher capacity radiator. The R also has more standard equipment both interior and exterior (like active diffy, exhaust, larger tires and high perf brakes) which add extra pounds here and there.

The performance/acceleration numbers of the R comp'd to the base XK are huge especially in qm trap speeds (the R is 119-120mph) that's 911 turbo territory my friend.