I bought my 2014 Q50 used when still under warranty. Test drove the car and seemed fine. Shortly after purchase I noticed a whistling sound originating from near the firewall when the A/C is engaged. It's the type of sound that is faint but definitely audible, even when the radio in on. Took it to the dealership for a warranty repair and was told that the whistle was a characteristic of the car due to freon passing through the A/C evaporator. I was told that the problem in know by Infinity but they refuse to repair under warranty. This is ridiculous for a car of this caliber. I have owned Datsun products, Nissan products and an Infinity G35 which I ran to 250,000 and loved. I will probably rid myself of this car soon and that will be it for me and Nissan.