I usually get this same kind of smell through vents and if i go outside i can smell it through front grill . But it only happens on long drives or hot days
This could be oil blow but from lack of a catch can or Air Oil Separator. Under normal conditions, the crankcase gases exhaust into the airbox. These gases tend to have higher levels of oil mist under boost. This mist gets burned in the combustion chamber , possibly causing these smells. Just a theory..
