EEEeeee I've ALWAYS wanted to lap a JCW. I think they would just be a bundle of fun, plus I'm sure you can just nail the gas out of corners like nothing else. I really like lapping FWD cars.
Also I never, ever used sport mode when on the track but used it on the highway/freeway. It felt like my feet were made of lead on the track, but it was nice on the freeway to just dab the throttle and gain 40km of speed, haha.
The JCW is more fun on a track than the M3. Its a very forgiving car, and the handling just never quits. Every time I exit a corner I realize I could have given it more and the car would have behaved.
Of course its always that just a little bit more that ends up getting you in trouble.