We decided to buy the car, a Giga REx with all options except 20" wheels. Picked it up yesterday. We'll continue to try to sort out the tank issue and if we can get the 2.4 gallon capacity somehow, great. If not, we'll live with it. This is going to be a great car even if the fuel tank has been screwed with.
Will report back when I hear from my friend in Belgium. Since we decided to go ahead with the purchase, i told him that his visit to the dealer there wasn't urgent, but that I would still appreciate hearing the result of his inquiry in the next couple days or so.
Thanks, Tom, for the excellent further info.
i3 REx (Andesite Silver, Giga interior, all options except 20" wheels)
June 3, 2014 to present