I bought a new Corsa SE 1.4 petrol auto which we collected last Friday. After about ten minutes we got on the M1 and after about five more minutes there was a big white cloud of smoke from the back. My wife, who was following, said there was strong smell of burnt oil. I slowed down and the smoke gradually dissipated. The car continued running smoothly at about 40mph. I carried on and reached home without further problems. I checked the oil and checked for oil leaks, but everything seemed normal. We were then away for a few days so only on Monday did I contact the dealers. The sales manager looked into it and said his top technical man could not explain what might have happened. He said he had checked the fuel receipts and it had not had any diesel put in it. The car seems to be running perfectly right now. I wondered if you might have an idea as to what might have happened.