What’s your car’s mpg? 25? 35? Maybe you have a Prius and you’re proud of that 51 on the highway? Well stifle it because the Volkswagen XL1 is about to take the ball and go home. VW says the two-seater will be the most fuel-efficient car in the world, using a plug-in hybrid system to achieve an ungodly 261 miles per gallon. It’ll take nearly 13 seconds to get to 60 mph on the 47-horsepower, two-cylinder diesel engine, but again: 261 miles per gallon.