The Antro Solo seat 3 people, and the Duo is 2 of the Solos backed up to each other and connected; resulting in a car that seats 6. I'm skeptical of this feature, too. Here's their webpage in English: http://www.solo-duo.hu/main.php?lang=en
But the Solo is feature packed all on its own:
it is a diesel/solar/pedal/electric plug-in serial hybrid. Primarily the battery starts out on it's own, supplemented by the solar panel and/or the people pedaling, and then the diesel engine kicks in to charge the battery. It is rated at 1.8L/100km (130mpg US)
It weighs less that 350kg (772 pounds).
Cd is less than 0.22