Well, now another update on my exhaust fumes in the cabin problem. I never got to bring the car into service to explore this yet. Thought it fixed itself. Curious that another poster said the problem disappeared after a while. Mine did too, but then I noticed that it seemed to return recently. Then it went away again. Why?
I really think it now has to do with the outside temperature, and the car's climate settings. For most of this winter now, no smell. All perfect. Then, we had a day when the outside temperature went above 50'. I started the car. I forgot to turn "auto" off. I backed up out of my driveway. The exhaust smell was back! I drove off, the smell disappeared. What?
Is there a sensor in there somewhere that stops outside air from being drawn in (plus fumes) when the outside temp falls below 50'??? And if the outside temp is over 50' does this sensor allow outside cool air in to augment the air conditioning if needed????
But, even if this is the case, why is engine exhaust able to enter the cabin at all? I suspect the problem will be back in the spring, disappear in the summer (no more cool outside air), will be back in the fall, and will then disappear again in the winter.
Turning "auto" off, seems to help, but not completely.