The previous owner of our car also owned a dog; which, from how the car smelt when we saw it in the showroom (admittedly before it had spruced up for sale), seemed to travel quite a lot in it.
It’s now autumn... and the car needs heating up. And the windscreen needs demisting. Which involves warming up air that has to go past the cabin pollen filter, which imbues it with a canine whiffiness.
Time to change the Pollen Filter!