1. See if you can find out the maintenance history on the vehicle from BMW. If it's been in the shop for just normal routine maintenance items (brake pads, rotors, oil changes, etc.) and not in the shop every other month for non-routine issues then that's a good sign.
2. Run a carfax. I have an active account for another week, so if you want to drop me a PM with the VIN I will be glad to run it for you and shoot you the results in email.
3. Consider having an independent mechanic give it a thorough inspection. Could save you a lot of headaches down the road.
and :xoutpost: