Here's a good link and discussion about future fuel economy. When I first read it I thought the 1L designation was for engine size but its about going 100 KMs/Litre (267 MPG).
http://gas2.org/2008/05/07/vw-confirms-1l-concept-will-become-reality-in-2010/
http://gas2.org/2008/05/07/vw-confirms-1l-concept-will-become-reality-in-2010/