"Knockout" brands of cleaners has a very good cleaner for removing odors, usually specific for either smoke or pet odors. REally all you need is a good brush, gloves, and a wet vac unless you rent a machine to clean carpet and upholstery. Generally, if its seeped into the foam of the seats, you pretty much will never get it all out, but knocking it down with cleaners, using seat covers, a car refreshener will do the trick enough for all but the most sensitive or allergic folks, I mean, I don't care who says it, most folks cars stink in one way or another, even if someone has just bought a new car, for a few days, people sometimes use the most god awful aftershave, or perfume, or laundry detergent, or super strong sports antiperspirant deoderant, apart from sun block lotion, I worked as a car detailer for awhile, and folks alot of time had way too high expectations many times, so, you can clean real well and get that "new car" smell formula from the auto parts stores and apply liberally, errrr, if reselling a car is where you are heading, or a complete reupholstery of the entire enterior, with panel replacements, an allergic person should completely avoid a smokers car, unless it is very cheap and unavoidable.