I initially bought the 2000 BMW Sport Wagon used with just 20,000 miles. It ran great with no problems until it went past 60,000 miles. After 60,000 miles I've had frequent phantom problems with the check engine light (and yes, I've checked the fuel cap every time...it was fine). I've had plastic bits breaking in all 4 windows regulators (one of them twice) and the sunroof clips (I hardly use the sunroof too). I've had electrical problems with the air conditioner, anti-lock brakes/traction/stability control, rear view mirrors and door locks. But, that's not all. I've always taken it to the BMW Dealer for repairs and maintenance to make sure it was done right. I think I got the lemon!
Drives great when there are no problems. Love the driving dynamics and solid feel of the wagon.