As someone who has done 18 years worth of track days I feel very qualified to answer this.
Mothers R3 Racing Rubber Remover.
You will get people suggesting tar remover and various other things, but nothing has come close to this in my experience. It's literally designed for the job.
Many years ago I used to track an Exige S2 (white) I'd come home and the car would be covered in rubber.... I tried everything back then, but what did work a treat was some Mer polish.
