Volkswagen is to produce a 2-seater car that it claims will do 313mpg equivalent.
The car will use an 800cc diesel hybrid powertrain, have a very streamlined shape, and will be made of lightweight materials.
The plug-in hybrid will also be able to travel up to 50kms on electric power alone.
No price guide has yet been released, but the XL 1 will go into production later this year. It will debut at the Geneva Motor Show the week after next.