Ingo Barenschee for Volkswagen

Doha, Qatar—For over a decade, VW's been working on an automotive holy grail—the "1-liter" car. It's a vehicle that can travel 100 kilometers (62 miles) using just 1 liter of fuel (0.26 gallons). This comes out to an astonishing 235 mpg. A prototype first saw the light of day in 2002—a 640-pound tandem two-seater powered with a spectacularly noisy 299-cc, 8.4-hp single-cylinder diesel that gave a top speed of 74.6 mph, a 0-to-50 mph time of 32 seconds and fuel consumption in the 220-mpg range. Economical, yes, but too impractical for daily use. Even VW's then chairman, Dr. Ferdinand Piëch, who drove the prototype from his office in Wolfsburg, Germany to the VW shareholders' meeting in Hamburg, recording 264.3 mpg (U.S.) at an average speed of 43.5 mph, said, "We will never build a 1-liter car."

But development continued, because, as Piech said, "We could gain the knowledge to build a 2-liter car." Before the 1-liter prototype was retired to the company's museum in Wolfsburg, I had a chance to drive it. The experience was enthralling and offered a glimpse of a future where supercars are no longer huge, heavy V8 leviathans, but instead are delicate, gossamer creations capable of being coaxed for miles on a thimbleful of fuel. There was even an ethereal mode of operation called "sailing," where the motor stopped and the exceptional aerodynamics and high-pressure tires allowed the car to glide silently for miles.

Then, at the 2009 Frankfurt Show, we saw the second prototype, the L1. This car retained the tandem seats but used an electric-hybrid powertrain with a two-cylinder diesel engine. It was faster—with a 100-mph top speed—and capable of 157 mpg. Dr. Piëch's dream was starting to become a reality. And this past week, at the Qatar auto show, VW revealed its third version, the XL1.

The Specs

The XL1's most dramatic departure from the L1 is its side-by-side seats. The switch came about because VW didn't think customers would accept the tandem arrangement. Since side-by-side seats increase the width and drag of the car, front-to-rear to minimize that effect. With a frontal area of 16.15 square feet and a drag coefficient of 0.186, the XL1 is one of the slipperiest cars in the world. It's a shame that the tandem seats have gone, though, as they helped make the XL1's antecedents so special and slightly bonkers, harking back to Buckminster Fuller's 1933 Dymaxion car or Fritz Fend's 1958 Messerschmitt Tiger.

The plug-in hybrid XL1, however, is as modern as the hour. The chassis is a 507-pound carbon-fiber monocoque with dramatic front-hinged scissor doors that's nearly 13 feet long, 4 feet tall and roughly 5 1/2 feet wide. It's a streamlined shape that appears to have been carefully sculpted by artists. But Walter de'Silva, head of VW's Design Group, says, "The car came out of the wind tunnel like that." Even so, the felt-tip fairies spent over two years nibbling away at the XL1's details to improve the aerodynamics; "it was incredibly intensive," says de'Silva.

In the last decade, the VW Group has been working on ways to make carbon-fiber bodies reliably and economically. This method, known as advanced resin transfer molding, allows the carbon fibers to be aligned in the direction of the forces, before they are shaped and mixed with resin and formed in the molds. With Austrian specialists Carbo Tech Composites, VW is using a similar construction method for the forthcoming Lamborghini Aventador supercar, but the carbon-fiber chassis is still some 80 to 100 times more expensive than one made from conventional stamped-steel panels. Dr. Harald Ludanek, VW's head of vehicle engineering, says, "To do this car in aluminium would have resulted in a 20 percent increase in weight, but it would have been 40 times less expensive."

Driving the rear wheels is essentially half a 1.6-liter TDI turbodiesel engine. It's an all-aluminium unit, using plasma-sprayed bores instead of iron liners. Displacing 0.8 liter, it produces 47 hp and 88.5 lb-ft of torque. A 27-hp, 74 lb-ft electric motor is sandwiched between the engine and a seven-speed twin-clutch transmission. A 5-kwh lithium-ion battery pack lives in the rear with the powertrain. In normal hybrid operation, XL1 starts in electric mode and stays until the driver floors the throttle, speeds exceed 62 mph, or the battery is depleted below 20 percent of maximum charge. There's an EV-only mode, in which the car remains on electric power until the battery has just 10 percent of its charge (typically about 22 miles), whereupon the motor starts to charge it and drive the wheels. Recharge time with 240 volts is just over an hour. The XL1's top speed is limited to 99 mph, and it can accelerate to 62 mph in 11.9 seconds. Fuel economy is tricky to determine since fuel use is supplemented by electrons, but on the NEDC (Europe's version of the EPA) Combined cycle, the XL1 returned 261.4, which should provide a 340-mile range from the paltry 1.8-gallon fuel tank.

The Drive

Climb over the carbon-trimmed sills and the cabin is surprisingly roomy. With the staggered but close-set seats, there's a pleasing but not overfamiliar intimacy. That interior is where the designers had the most influence, and it shows. "We wanted it to be recognizable as a VW, but also to show how it's unique," says British designer Andrew Hart-Barron. The result is a pleasing mixture of VW Group instruments, with a splendid piano-black ventilation duct that runs across the dash. It's classy, and like no other car.

The passenger seat is fixed, but the driver's moves fore and aft, and the backrest tilts. The steering wheel also adjusts for reach. The very tallest might find the roof encroaching on their coiffures, but I'm six feet tall and had headroom to spare. The only criticism might be the lack of space to rest my large and redundant clutch foot. As with all scissor doors, it takes a firm pull to get this one up and down, and without conventional door mirrors, the XL1 displays television images of what's going on behind you on door-mounted screens. They're strange, but you quickly get used to them.

All around are weight- and energy-saving innovations: Light-emitting diode lamps are used for even the headlights, and narrow-gauge wiring with tiny electrical fuses runs through the car. Movable louvers in front of the radiator and a flat underbelly reduce drag.

One push of the starter gets the systems fired up, and after a five-second delay, another push prepares for takeoff, which is signified by a green "RDY" signal appearing on the dash. A well-sprung throttle pedal inhibits speedy getaways, so the driveline remains in electrical drive at first, but you immediately notice the direct and superbly weighted steering, which allows you to place the car accurately through the turns. Unassisted calipers squeezing ceramic brake rotors need a firm push from the brake pedal to activate, but are linear in operation. The argument still rages at Wolfsburg as to whether the brakes should have an electrical booster, which would add weight and complication but lighten the pedal pressures.

On electrical power, the 1795-pound VW feels zesty but hardly quick. Push the throttle harder and the parallel-twin diesel fires up with a thump from the driveline and a mechanical whir from the back. Refinement is only nascent, and that needs work before production. The ride is reasonably good on the special narrow Michelin tires, but over potholes or low expansion joints, you feel the unbending stiffness of the body shell. With all guns blazing and both propulsion units providing the urge, the XL1 is pleasingly brisk, and the fat slug of electrical torque wafts it forward between 40 and 60 mph. Road noise is quite audible, though, and when combined with the whirring motor and engine, the interior cacophony is borderline unacceptable. You can also hear the cooling fans mounted in the dorsal fin over the engine bay.

On my short drive around Doha, it was difficult to get a complete gauge of the handling, but the center of gravity is low, so it's reasonably stable. If there's one thing the XL1 has lost compared to its predecessor, it's that otherworldly easy-gliding nature. Blame the hybrid powertrain, which adds a considerable amount of heft.

The Bottom Line

"The XL1 is a genuine Volkswagen, which could come into small series production in 2013," says Professor Martin Winterkorn, VW chairman. His boss, Dr. Piëch, says it should be "built in reasonable numbers" and "affordable." Let's read between the lines here. With its advanced resin transfer molding system, VW can make an absolute maximum of 24 carbon-fiber bodies a day and would have to take a financial loss on each one to make the car affordable. Most likely, the German giant will build a couple thousand XL1s and use the car's powertrain for other fuel-economy specials. How much will the XL1 cost? No one from VW would say, but I'd guess a ceiling of $65,000 in the U.K., where a fully loaded Golf GTI costs about $42,000. Do you want one? You bet you do. The XL1 is a new breed of supercar, one that is every bit as extravagant, technical, beautiful and exotic as a Lamborghini or a Ferrari, but that points to a new kind of world where we understand that natural resources are finite and precious, and maybe a new style of driving where we try to conserve them.

This content is created and maintained by a third party, and imported onto this page to help users provide their email addresses. You may be able to find more information about this and similar content at piano.io