Volkswagen has just announced its most fuel-efficient car, the XL1, a truly inspirational prototype. The car is powered by an 800CC turbodiesel engine and a small electric motor. The two seater holds 2.5 gallons of gas, so at $4 a gallon, will only cost $10 full a full tank. Since each gallon of gas brings 261 miles of driving, $10 buys you 650 miles on the road. Just to be clear, that’s like driving from San Francisco, California to Mexico on a single tank, for a single $10 bill. Truly impressive.