Hi Geoff. Your problem intrigued me, so I did some research on it. It looks like quite a common problem. As I understand it, the exhaust is by the nearside front wheel, which is near the air intakes used by the climate control. So as you fire the engine up, the climate control sucks some of that exhaust gas up though the air vents into the cabin. There doesn't seem to be a fix for it, other than maybe not having your aircon on when you start the car. It doesn't seem to be an indicator that something in your car has gone wrong, which is obviously good news. I hope this helps. Adam.