The carbon filter goes in a wider slot. On my 2000, I had to cut away a plastic molding spru blocking the second slot with a dremel cut-off wheel. The way it's built, you could then use either filter. One further note. The carbon filter is denser and the fan does not get as much air thru it. I am told that the dealer can adjust the fan speed range for that filter, which on the newer models is called Interior Air Quality System (IAQS), and comes with a sensor to tell you when to change the filter. I have not done this and reverted back to the original filter to improve the air flow for the summer. I'm weighing the cost of using more filters and the "adjustment" against the benefit now. It did seem to cut down traffic smells, but I seldom encounter heavy traffic.