hello. just purchased a 95 740i a week ago. i bought it with the check engine light on. i knew the oil hadn't been changed. the engine runs great though. i made sure i fill it up with premium gas. added stp gas treatment. check engine light went off today.point is make sure u use premium gas. next is ac. compressor blows. a little cool at night. if not a leak,i'll ad freon.if so, i can get one really cheap. these cars are not that expensive to maintain. long as the engine and transmission are fine u can replace parts really cheap. just buy used parts. owned a mercedes diesel and didn't have any repair issues. so it's a myth about maintenance unless u want to pay the dealer.