???FACTS OF VW XL1

.Qatar isn’t exactly short on petroleum reserves, but Volkswagen still decided to unveil its latest fuel-sipping show car — the XL1 concept — at the country’s auto show. While our first look piece has the full skinny, we’ve compiled some of the major highlights surrounding the latest evolution of VW’s 1-Liter car project.

Third Time’s The Charm

The XL1 is not Volkswagen’s first stab at crafting a small car capable of traveling 100 kilometers on a liter of fuel. After chairman Ferdinand Piech pushed the project in motion back in 1999, a rudimentary prototype, known as the 1-Liter (or 1L), was up and running by 2002.

Engineers continued evolving the idea, and an updated car (now billed as the L1) was shown at the 2009 Frankfurt Motor Show. Although that car wore styling in keeping with Volkswagen’s current design DNA, it still remained a lithe, tandem-seat four-wheeler, albeit now with a diesel-electric hybrid drivetrain.

Longer, Lower, Wider

Unlike the first two takes, however, the XL1 moves the passenger’s seat adjacent — not aft — of the driver. VW says the car is five and a half feet wide (almost two feet wider than the L1), yet at 45.5 inches tall, it’s quite short — lower, in fact, than a Lamborghini Gallardo Spyder.

These factors, combined with a small frontal area, a tapered profile, and other tricks like active louvers, allow the XL1 to excel aerodynamically. Volkswagen says its coefficient of drag is roughly 0.186 Cd, only slightly worse than that of the original 1-Liter prototype (0.159).

What’s Under The Hood?

Like the L1, the XL1 is a hybrid, although Volkswagen has configured the system to function as a plug-in hybrid, allowing the car to travel under electric power until the lithium-ion battery pack is depleted.

That electric propulsion is provided by a small 27-horsepower electric motor, which is sandwiched between an equally small 47-horsepower, 0.8-liter two-cylinder turbo-diesel and a seven-speed dual-clutch transmission. In pure EV mode, which is triggered by pushing a dash-mounted button, the XL1 can travel roughly 22 miles. Mix in the TDI, and the vehicle’s range expands to 342 miles.

The real magic, however, lies with the XL1’s fuel economy figures. Volkswagen says the car is capable of traveling 100 kilometers while sipping only 0.9 liters of diesel — better than the L1 concept (1.38 liters per 100 km), and roughly on par with the original 1-Liter tester. For the record, that’s roughly the equivalent of 261 mpg.

How’d They Do That?

Certainly, the carefully tailored aerodynamic shape plays a significant role in the XL1’s fuel economy, but so does its weight. At 1752 pounds, the car is quite light (200 pounds less than a 2011 Lotus Elise, in fact), which only reduces how hard the diesel-electric driveline needs to work.

That svelte figure, however, didn’t happen by accident. VW engineers worked hard to incorporate lightweight materials throughout the car. Unsurprisingly, like the first two one-liter concepts, the XL1 uses a lot of carbon fiber reinforced plastics — in fact, roughly 21.3 percent of the entire vehicle is crafted from the composite material. CFRPs are used to form not only the exterior panels, but also the anti-roll bars, along with the monocoque structure itself.

Weight is further reduced through the use of polycarbonate windows, aluminum suspension components and brake calipers, magnesium wheels, and ceramic brake rotors.

Will It Reach Production ?

Volkswagen has long promised a 1-Liter car could enter production by 2013. Although previous concepts were technically interesting, this appears to be one of the first that actually has a fighting chance at series production. In fact, Volkswagen CEO Martin Winterkorn recently told Automotive News the car will launch initially in Germany, before ultimately reaching both the U.S. and Chinese markets).

We wouldn’t expect the XL1 — or something like it — to be an inexpensive proposition, but it appears Volkswagen is working hard to strip some of the costs away from the manufacturing process. In fact, the entire 1-Liter project led the company to develop advanced resin transfer molding processes, which it believes is a cost-effective way to mass-producing CFRP components.

That said, don’t expect VW to churn out XL1s in the same fashion it stamped out Type 1s in its heyday. The automaker has indicated this initial production run may be limited to 100 cars, and it’s still unknown just how many — if any — will be made available to consumers.