I don't want to be taken down for being against the grain but I don't think I have ever had a fixed air freshener in the car, mainly because I think they look cheap and tacky.
If I did have to freshen it up I'd use that Autosmart Blast.
I find genuinely the best way to keep a car smelling fresh or 'like new' is to clean it regularly on the inside and not keep too much crap in it.
I regularly shampoo the carpets / seats in all my cars and use Sonax cockpit cleaner on all the plastics. My Fiat has done 125,000 odd miles and still has that 'new car smell' - I know because I owned it from Ex-Demo at a handful of miles!
I'm a strict non smoker and no one smokes in my car - if I did I guess I would need a fixed one.