 Not every vehicle has a cabin air filter. Most do today. And it just literally helps you keep cleaner air coming in. And also, if you get trapped the mold spores and the dust and the dirt before it gets to your evaporator, then you don't grow mold on your evaporator so easily. The evaporator is the part that cools inside the car, so it sweats all the time, so it stays damp all the time. So if you get the mold spores and the grass spores on there and