Strange that your friend couldn't drive it that fast. Base MINI Coopers (non-S) took 1st and 2nd in their class (H stock) recently, results at http://www.scca.org/amateur/solo2/prosolo/2002/atwater/results.html. I've never auto-x'd or solo'd so I don't know anything about it, I just thought I'd post the results. BTW, base Cooper S comes with all-season runflat tires so they may well not be the best for the track. I don't know how the MINIs were prepped in Cali.
S2000 is RWD, right? Maybe your friend isn't used to FWD?