Volkswagen's 170 mpg car

In 2002, Volkswagen designed a concept car that could go 100 kilometers on 1 liter of fuel, equivalent to about 235 mpg. This year, Volkswagen shows off the second generation of the 1 liter concept, the L1, with the intention of production by 2013. Using an extremely light and aerodynamic body and a diesel-electric parallel hybrid power train, the new L1 falls short of its fuel efficiency goal, requiring 1.38 liters of diesel to cover 100 kilometers, or 170 mpg. Still, not bad.

Volkswagen designers looked at glider design to evolve the L1 concept, resulting in a narrow body with two seats in tandem, the single passenger consigned to a rear seat. Access to the L1 is through a hinged canopy, which should inspire Top Gun fantasies for the driver. Furthering those fantasies are the camera-based rearview OLEDs, offering a 180 degree view behind the car. In keeping with the high-tech cabin, the speedometer and other instruments are all virtual. Although we didn't see a stereo in the cabin, there are volume controls on the steering wheel.

However much the cabin might inspire feelings of piloting a fighter jet, the performance will make the driver envy scooter riders. The L1 takes 14.3 seconds to get to 62 mph. However, the top speed is a reasonable 99 mph. To power the L1, Volkswagen developed a new .8-liter version of its TDI engine with only two cylinders. The driver can select between Eco and Sport modes: in the former, the engine produces 27 horsepower, while in Sport it peaks at 39 horsepower. Being a diesel, its torque is much higher, hitting 74 pound-feet at 1,900rpm.

Where Volkswagen gets really clever is incorporating a hybrid system into its seven-speed Direct Shift Gearbox (DSG). The DSG transmission uses two computer-controlled clutches to provide automated shifting with manual transmission performance. A 13 horsepower electric motor situated between propeller shaft and transmission supplies additional power to the car. The motor is powered by electricity from a lithium ion battery pack in the front of the car. As a hybrid, it has a start-stop system, shutting down the engine when stopped in traffic. With its 10 liter fuel tank, Volkswagen estimates a range of 416 miles.

Although the L1 may not seem all that practical, the research that went into designing it, including engineering the hybrid system into the DSG, could be applied to other cars, increasing their efficiency.