well, #166's response is a bit of a joke, I think:
Wolfsburg is at an elevation of 55m above MSL, and Hamburg at 10m. That's a gradient 45 metres over 170 km, and it's really quite ridiculous to argue that such a gradient contributed to the extraordinary mileage. Plus, the argument about empty highways on sundays is refuted by the very picture shown, with quite a few vehicles on the road. The VW 1L was always a technology demonstration project, and never intended for production in that particular form. VW was considering a 1L car, but not based on this concept. The 1L was quite an amazing concept, but everyone knew from the start it wasn't practical. Still, cool to see what extreme engineering can accomplish.
M