If you have not had the opportunity or need to really punch your C-Max it might take you by surprise. I had to punch mine to merge into some fast moving traffic and it met the challenge. However, when I looked in the rear view all I could see was a thick cloud of smoke. So thick that I couldnt see the cars that were in the lanes behind me! My son was minute or so behind me and saw the cloud. He phoned me and insisted that I pull over. We checked the oil and it was fine. Then we proceded to drive and I punched the car again. This time no cloud. We checked the oil again and it was fine. There were no warning lights or indicators that anything was wrong. Very strange.