It extends beyond the gas tank layout to the rear passenger seats, making it independent of the magic seat layout.
It basically becomes the entire floorboard of the passenger cabin.
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On a side note, I just noticed that the AWD versions have two fuel pumps. I didn't realize until I looked it up just now at hondapartsnow website. Then I googled and saw this:
The Fit and FWD versions of the HR-V both have centrally located fuel pumps, but that wouldn't work with the driveshaft going down the middle.