It doesn't seem so hard to slap the engine out of a wrecked sportsbike into the i-MIEV body. But a small Diesel, to run either on biodiesel or pure vegetable oils, would also be a nice option
Too bad the availability of small Diesels back there is too focused on off-road boat-anchors
Kohler Engines: KDW1003: Kohler Diesel Liquid-Cooled: Product Detail: Engines