Some manufacturers left the smell to chance (the chemical odors of carpet and upholstery) and others were obsessed with it. When I swapped out my old interior for the new interior, the Fiat smell of the interior nearly vanished. I can still smell the cardboard, mildew and years of fuel odors that permeated the dashboard, but that's about all that's left. The seat foam was nearly odorless...despite a slight smell of "old".
Under the hood is another story...everyone got it right...burning oil, fuel leaks, etc., make up that smell. When I had them all fixed, there was no unique smell...now it is back.
