Because that's the BMW way! I don't think it has anything to do with which side the driver is. Most, if not all, Bimmers have the filler cap on the "right side". A MINI is still a MINI, but it "is" a member of the BMW family after all....not a bad thing whatsoever imo....why on earth change the gas filler to the other side? Made for an embarrassing moment at the gas pumps the day I took delivery...