Q. I heard that its maintnance is very costly as the break pads needs to be changed at every 10000 km. Is it true - Cooper 3 DOOR?

Changing the brake pad depends on the driving style, traffic condition etc it not fixed that is should be changed after 10000km. For the maintenance cost suggest you talk to your nearest service centre.

Maintnance is not that much costly...and break pads need to be changed at every 10000kms