I think I've been fortunate to have never had a car that stinks of ciggies, my ae86 now smells like maple syrup after my heater core leaked all over the carpet.

Civic doesn't have a distinctive smell but I guess its kind of smells like a mechanics car from the previous owner, kind if like engine oil. Had diff oil on the carpet at one stage, luckily thats gone as that shit stinks.

I remember a mates charger r/t had the best smell, smelled like warm seat vinyl... not sure. But you could leave your jacket in it over night and when you chucked it back on it smelt like triple webbered goodness