I totally agree they are different cars, The XK obviously wont be as fast or exciting to drive as the E92 M3 but it is still a very special car and I think it targets the 6 Series more. However, The XKR is in testing and I think it might be a 4.3 supercharged V8, I really cant remember but it is going to be fast. I seen some spyshots and it has quad exhausts and hood vents and the intakes on the front bumper look different. I think the XKR still be targetting the M6 and not so much the E92 M3, although it will be interesting to see how they both compete...
btw ksfrogman you are right too, damn Supra's are fast lol and for a 13 year old car look brilliant, (I have a Veilside Supra)