About seven months ago, Rebecca Harrell and Josh Tickell, co-founders of the Veggie Van Organization and producer of the upcoming film FUEL, attempted to drive across the U.S. with just 25 gallons of gas.
It sounds crazy, but it actually worked with only 50 gallons of gas!
The “Algaeus” (a tricked-out hybrid Toyota Prius) gets 150 mpg because it runs on an algae-based biofuel.
Sapphire Energy says it will soon be producing green fuel that can compete with fossil fuels cost-wise.
Sources:  http://www.inhabitat.com/2009/09/09/first-algae-powered-car-attempts-to-cross-us-on-25-gallons/