Discovered the Air conditioner wasn't working as it should. Initially I thought that it was just the way things were but , as warranty was just about up, I decided to take it in to have it checked. I wasn't imagining it after all and after two weeks with a gas powered loaner I got the car back with functioning air conditioning. I should add that for a month or two I had noticed a humming noise whenever I turned heat on during the winter. I was told that they did not find anything wrong and so I thought the sound (like a mid sized trunk running in the distance) was what it should be when heat was running. Since having compressor replaced I no longer hear that sound :) 2015 I3 BMW anywhere between 3-5miles loss in range when set for comfort.