Many modern European vehicles are equipped with a cabin air filter. Just as the engine air filter protects the live of the engine, the cabin air filter’s job is to protect us, filtering out harmful airborne particles from the air blown into the cabin. Activated Charcoal filters offer additional protection, and can be differentiated from standard filters by their dark charcoal color. Cabin air filter replacement is an often overlooked service. It is recommended that you inspect a vehicle’s cabin air filter every 12 months or 12,000 miles. If your HVAC system smells funny, this filter is the first place to look.