I read from others on here that the 400 has a larger storage under seat. So this weekend, I decided to take the 400 to my fav. BBQ restaurant to pick up my usual 3 trays of take home meats (that I KNOW fits under the 650's seat). I was shocked to find out that I couldn't fit all 3 foil trays under the 400's seat, but only 2. Apparently, that tire shape protruding into the bottom of the seat takes out ALOT of usable storage. Good thing I put a top box on the 400. Or else I would have had to eat 1/3rd of all them good BBQ ribs b/f heading back home.