I'm wondering if there's a solution to this.
For the driver's seat, there's 3 adjustments;
the angle of the back (from the lever on the side of the seat),
how far up the seat is (from the lever under the front of the seat), and
the angle/height of the bottom of the seat (from the wheel on the side of the seat).

Now, for the passenger, they don't have that bottom of the seat adjustment and
there's this huge gap between the backrest and the bottom.
Is there any way to close that or adjust it?

yeah, i've got that problem too. whenever i put things like my mail or whatever, they tend to slip out the back.

Gerald.. you hit the nail on the head... I HATE it when that happens... >.<