The 261-mpg Volkswagen XL1

After working on the idea for over a decade, Volkswagen has revealed the near-production version of the XL1, a two-seat, plug-in diesel hybrid designed to be the world's most energy-efficient automobile. VW estimates the XL1 can get 261 miles to the gallon — although with a time to 62 mph of 12.7 seconds, it won't get there quickly.