I took delivery of my Model X 75 in March. I have 3,400 miles on the car. While on my way home from work I heard that unmistakable sound that we all have heard....grinding, as if you have no break pads. Turns out that my rear Caliper came loose and was grinding against my new 22" onyx Wheel that cost be $5,500.00. Had to call Roadside assistance and get towed. It is sitting at the shop now. I am waiting for my call to let me know how long i will be without my vehicle. I better get a replacement wheel. This is surely a quality control issue that could have had serious consequences.