Haha at my previous work there is a M3 convertible that is there literally all the time. Like Sunday 3 am it was there. I guess it's owner forgot about it? It has been there at least a year.
BMWs are definitely expensive as they get up there in years/miles in maintenance. You can take it to other dealers for oil changes but you still have to buy the filter and you definitely get strange looks. Electrical issues seemed to be the gremlin that affected my BMW; all of the following instruments worked sporatically: speedometer, gas gauge, engine temperature. On my mother's 330Ci the convertible top worked about 1/2 the time. Even after $3k+ in service: 2 times at independent shops and once at the dealer it still didn't work consistently. Nonetheless BMW gives you very tight response and short transmission throws.
I currently drive a 2006 Scion tC I'm much happier and it's a CHEAP car in comparison to a BMW. Oil changes are at least $25 cheaper and 30,000 mile service is 1/2 the cost.