There are a couple of remedies... You can try to take a very thin uninsulated wire with a long needle and place a few stitches into some of the seams, pass it through the seat, then attach it to any bare metal on the seat frame or some other grounding point (use a multimeter to make sure it is grounding out). Antistatic suits use a similar system. A few small stitches spread throughout the seams of the seat of very thin wire will work well to prevent static buildup and will be pretty much unnoticeable. I would take a few strands off a finely-stranded tinned copper hookup wire to do the job.
They do make antistatic sprays (makes fabric mildly conductive), but I doubt that would work as well alone in this application due to how well insulated the cabin is. It would help, however, especially in conjunction with the grounding.
With all the foam (is it Dow Impaxx?) in the floorboards, I would think that the cube is a little more prone to static buildup than some other cars.
A note of caution: always be sure to touch something metal on your car to ground yourself out when getting out before filling it with gas and never get in and out of your car when filling- especially during the winter. Static sparks can ignite gasoline vapors.