I recently rented a room IONIZER to remove musty odors in the finished basement. It isn't an airfilter but ionizes the actual cause of the odors. I left it in the basement for a day and wow all odors are gone sooooooo I put it my 64 88 for the night.
It removed all the odors....old cigarette odors,mold,mildew and grease smell.
My car didn't smell like an old 60's bar room closed for 50 yeaars but it did have some annoying odors. When I did buy the car I put a dehumidifier in the
car to remove any moisture that had built up while it sat for a few years but the affect was nothing like putting in the IONIZER.
They can be rented at rental stores or if you know someone in the cleaning buisness you can ask them.
I bet it works great in old musty trunks.
FYI: make sure when you put it in the car you block off the open window the electrical cord is placed......the last thing is to IONIZE the whole garage....jey thats an idea!!

 

Be careful if it also creates ozone. Hard on plastics and really bad on you in enclosed spaces, like a car.

 

Yes I know about the hazards. Kept in on just long enough to do the job