Volkswagen bills its XL1, a plug-in, diesel-electric hybrid, as “the most efficient car in the world.” The name reflects its claim to being the world’s first production “1-liter car,” able to go 100 kilometers on a liter of fuel—or 235 miles on a gallon. VW plans to begin selling small numbers of XL1s, likely in Europe only, by the end of this year.
The company went to extremes: Roughly as long as a subcompact VW Polo and as low as a Lamborghini Gallardo Spyder, the dolphin-bodied XL1 boasts a vanishingly low drag coefficient of 0.186. The carbon-fiber-intensive car weighs just 795 kilograms (1753 pounds), seats two occupants in offset side-by-side chairs, and integrates wing doors for easier entry and exit. A two-cylinder, 0.8-liter diesel puts out 35 kilowatts (47 horsepower), which combines with a 20-kW (27‑hp) electric motor, a seven-speed dual-clutch automatic transmission, and a lithium-ion battery. The result is a leisurely 11.9-second squirt from 0 to 97 kilometers per hour (0 to 60 miles per hour) and a 160 km/h top speed.
But the XL1 is about saving energy, not time: The power it needs to cruise at a constant 100 km/h is less than what a typical ride-on mower uses to cut the grass: just 6.2 kW (8.3 hp).
Fuel economy: 100 kilometers on 1 liter of diesel fuel (235 mpg) Aerodynamic drag coefficient: 0.186 Power plant: 0.8-L two-cylinder diesel, 35 kW (47 hp)