I'm confused . Could you elaborate on just how the car is involved?

what does it smell like?
death...decomposition of animal in duct
or wet/moldy?

where are ducts located? attic
basement or crawlspace

is the furnace new?

any modifications to ducts, returns
or anything that involved sealants?

more info please.

Hm... It does not smell wet, yet it doesn't smell as bad as animal decomposed.. The smell stinks yet not make me vomit.

The ducts are in the attic.

Furnace is about 7 years old

Nothing has been done to the ducts or returns.

srjohnt, I was comparing both the house and the car smell exactly the same.

OK, so you're saying that it smells like the car's exhaust? If that's the case, you may have a cracked heat exchanger, or a vent problem.

This post was edited by srjohnt on Sun, Feb 24, 13 at 16:10

have hvac pro check it out.
maybe he/she can put a name to the
smell.

gas furnace?

best of luck.

Thanks for all the replies. srjohnt, I need to clarify more; sorry for the confusion. It's not the car's exhaustion smell. The car had the exact same smell when the heat was running inside, as the house's. In summer, when the A/C is running, there is no funny smell either in the house or the car. The smell is not like bad emission, exhaust, engine burned, oily, or any industrial kind of smell

Is it a heat pump system?

Heat Pump Dirty Sock Syndrome

Yes, it is a heat pump.

OK...yeah, "heat pump dirty sock syndrome" makes sense