Swedish for “street legal,” The Baldos II is the most fuel-efficient car approved for street use in Sweden. It started out as an entry in the 2009 Shell Eco-Marathon road challenge. Built by engineering students attending Sweden's Lulea University of Technology, the Baldos II is a serial hybrid that runs on electricity and 100% ethanol fuel. The car is just over 8.5 ft. long, weighs just 485 lbs., features a carbon-fiber body, and consumes just 0.017 gals. of fuel per 6.2 mi. — but there is only room onboard for a driver.