I keep fairly complete records for all my cars.
On the BMW, I've had it since '93. When I got it, it had 59,000 miles on it, it now has 121,000. When I last totalled up my maintenance records, it was at about $4500. That is really almost all maintence parts (tires, oil, brake pads, rotors, etc.) and a lot of replacement parts (radiator, brake system parts, wheel bearings, etc.). I have done ALL the labor for service and repair myself, with the exception of a recent driveshaft replacement ($600, and by far the most costly single car repair I have ever incurred). So, about $560 per year on average, I guess, for parts only (if I paid the labor charges, the amount would have been astronomical, esp. for diagnosing and fixing problems, and the car would not have been worth it to me).
On the Porsche, I have had it for over 10 years now, but have only driven it around 15,000 miles total. So, the repair costs have been minimal. The biggest repair and maintenance cost has probably been yearly oil changes (12 quarts per change). I have spent some "unnecessary" money on it though. Like the night that I started cleaning the engine, removing parts to get better access and do a good job, and I ended up taking the entire engine and transmission out of the car! Just on cleaning material, powdercoating, cadmium plating, replacing of gaskets, hoses and seals, etc. (hey, gotta do it while you're there) I probably spent close to $2000.
On the MB, none, of course, its all covered for 4 years!