I like it because it really filters bad air outside. For example, during July 4th, I passed I-5 Santa Ana when the whole atmosphere was foggy from firework and the smell inside the cabin was pleasant and works like a charm. Downside is that it eats up range a lot because somehow Fan has to be at 9 (out of 11 scale). I would love to turn it on if the fan is adjustable with Biodense mode. So, how often do you turn on Biodefense mode?