Very nice concept, of which 50 cars were built. In the next video there is some information about this early VW 3L car - in german - but with some graphs and a test drive that begins at 4:16.
It's quite progressive for that time! 27 hp in normal mode, 40 hp with the supercharger activated. A semi automatic gearbox, start/stop, coasting with engine off, but also emissions were taken into account, with EGR and a particulate filter. We're talking about 1987.