Clean Out Permeable Materials
For serious smoke smells, you will need to get down and dirty a little. Start by vacuuming everything- in all the crevices, under all the mats and the seats. Then take out the mats and any other removable fabrics. You will want to clean them down with warm soapy water. Once they are cleaned, you can let them dry in the sun.
The upholstery- the seats and floors, will be a bit more difficult to get clean. You can wipe them down with a solution of Murphy’s oil, which is part oil and part water. Just follow the instructions on the container to find out how much of each you will need. Then you can wipe down the seats and floors lightly. You don’t want to apply a lot of the solution to them, as that will just permeate them with a different smell.
Alternately, you can use an upholstery spray cleaner. You can usually apply this directly to the materials or to a cleaning cloth. Let it sit for a few minutes before drying it off.
To make cleaning easier, you should remove any items from the car that you can. Any removable seats should be taken out. This allows them to air out, but it also allows you to get to many hard-to-reach locations and to clean the carpet under the seats.