My wife has a 12 month old FIAT 500 diesel. Today while driving it "made a funny noise" then started to accelerate. She put in the clutch and pulled over as the engine revved out of control; turning off the ignition did not stop it. All the time it was producing clouds of white smoke from the exhaust and after revving crazily for a short time it rattled to a stop; leaving a small puddle of oil under the car. The AA recovered the car to the supplying dealer (who has also maintained it according to the service schedule) who said it might be a problem with a turbo oil seal but they would need to investigate. So far the dealer has been fine, providing a loan car without asking and promising to get back to us once he has investigated the problem. My questions are; does the turbo oil seal explanation make sense (I've done a quick Internet search and can't find anything to explain the engine revving) and secondly do you think it likely that serious internal engine damage has resulted from the over revving?