We have a 2016 Civic Touring and at higher speeds we definitely can smell outside exhaust fumes coming in though the air circulation mode is set to "Recirculation" - the smell is especially strong once we pass any diesel trucks. We turned off all ventilation to check if the outside fumes come in through the doors/windows or gaps but once all ventilation was stopped the air got cleaner - so this definitely looks like something is not right with the "Recirculation" mode since in this mode all...
Air "Recirculation" mode lets in outside exhaust fumes at higher speeds
Air "Recirculation" mode lets in outside exhaust fumes at higher speeds