I think this shows how well it really works as I really haven't noticed it at all! That is, driving behind large trucks spewing diesel fumes, farm smells on my way to Sherman TX, cigarette smells from the driver in front of me causally flicking their ashes at me out a cracked window, and driving behind my friends race car with no exhaust smell at all! It really struck me today as a lady was again smoking heavily and we were in stop and go traffic and I saw the wisps of her second hand smoke just float over my X.... I was waiting for the smell...but then NOTHING. NOTHING AT ALL! In fact, I haven't noticed any bad smells at all while driving the X! This car is SOOOO nice!