Exhaust Odors

[Jim Briggs]

My 91 2002TQ (174K) has been great, but recently in the AZ winter,  
meaning no air conditioning needed or climate control on,  when just  
cracking a window or tilting sun roof I have noticed what smells like  
exhaust being drawn into the cabin.
At first I thought it was traffic I was following, but since have  
noticed it when there is no traffic around.
Does not seem to be noticeable with window al the way down.

I had it in for servicing and there are no leaks in or the seals of  
the exhaust. I asked about this being pulled into the cabin from the  
engine compartment, but response was that there shouldn't be any  
exhaust in the engine compartment.

Any thoughts on this situation or similar experiences out there?

Jim in AZ