I've recently picked up a 2003 S4 - 101k, On the way home from work this evening, with the windows open,I noticed the car smelt a bit 'hot'. It wasn't - sat at 90 the whole time. A few minutes later I noticed a bit of white smoke from the exhaust, disappeared quickly. About 5 mins late, again while it slowish moving traffic another puff of white smoke. I'm new to all this - any thoughts? Suggestions on what to do?