[andix]

Spend some money on a good cabine air filter. Especially cheap and midrange cars come with simple ones, that can easily be replaced with activated carbon filters. It may cost 50-100 usd every two years extra, but it’s worth the money if you have allergies. It also reduces bad smells from outside air.

For example mann-filter.com sell also biofunctional filters for many car models. They made a huge difference for me. And worked flawlessly for 2 years.