Well a bit of an old thread revival, but it saves starting a new one since I can continue on the last. Anyways, from my previous post on the 4th of February, would would have seen my filter looking like the following (and I mentioned that I should probably get a new one):
Well, I got a little lazy and never got around to changing it. When it was at that state, it would have been in the car for about 5,000km. Now another 2 months and 5,000km later, I finally got around to changing it, and well.... the picture kind of sums up why you should change it at regular intervals, bearing in mind I have my external vent open about 90% of the time.
The air smells so much cleaner now. It really does make a difference.