There are two sets of filter... the 2 under the hood: a five minute change - but the factory kind come with a real charcoal layer and the aftermarkets ones are cheaper and "OEM" gray and "charcoal activated". Not sure it matters.
Then there two more under the dash for "cabin cleaning". Access up via the foot-wells and a bit more difficult but I haven't tried it yet.
Jun 25, 2010 at 12:04 AM