Just started getting fumes (exhaust or crankcase blow-by) in the cabin through the ventilation vents of my 2012 2LT auto (about 32k miles). I notice the fumes after the car has warmed up and the car is stationary. No odor if I switch to recirculate, and no odor when the car is moving. Plan to schedule a trip to the dealer, but I would like to have some idea of the cause before I go. Any ideas?