I recently bought a 2005 Cooper S (6 speed manual). The mileage is getting close to 100k, and I wanted to see what components start to fail around that mark so I can take care of them early (I'm close to 85k currently). So far I've replaced the spark plugs, cabin A/C filter, and I'm doing transaxle gear oil this week. I already know a clutch replacement will be in my future soon....
EDIT: Just realized generation and production date may factor in to this... so here you go: R53 2005/08