I just bought a 750 bmw work 20k miles on it. It
drives great but if it was to ever break down on me
will it cost a lot of money
With only 20,000 miles, you have a long way to go. What year is your car? Sure all cars cost money to maintain. What did you pay for your car? I wouldn't be too concerned except you should plan ahead, BMW repairs can be expensive, but, you should have known that.
Yes! If your worried about cost shouldn't own one
Anything European will cost more to maintain and repair. Asian vehicles are the next highest, but still Amercian vehicles are still the cheapest even with all the high tech garbage, and GM is still the cheapest to maintain and to repair.
Find an independent BMW garage in your area to save on repair costs and avoid the dealerships after your warranty is up.
What model year is your car?