Send your complaint in writing to the dealer principal of the dealership you bought the car from stating your misgivings at this time and stating that if the whine does not subside by 8000 miles you want the car replacing with an identical one that does not have the fault or you want your money back. If the dealer wants to buy the car back from you now for what you paid for it state that you would be happy with that too. End the letter by post office special delivery, keep a copy and staple the certificate of posting to the copy so it becomes a matter of record.