2013 Volkswagen XL1 (© Volkswagen of America, Inc.)Click to enlarge picture

The XL1 is Volkswagen's take on the future of super-fuel-efficient transportation. With its combination of lightweight construction, hybrid diesel and slippery shape, the XL1 hypermiler delivers a stunning 260 mpg.

For the super-fuel-efficient Volkswagen XL1, form follows function. You'd be forgiven for thinking that the aerodynamic little blob is some kind of high-speed bicycle at first glance, but as polarizing as its aesthetics may be, you'd probably be shocked to learn that the XL1 gets more than 260 mpg. Volkswagen pulled out all the stops to build this third iteration of its hypermiler, making more than a few technological advances in the process. But can we expect to see any of that high tech in the Volkswagens we can actually buy?

The short answer is we won't see much that we haven't seen before. The XL1's parallel hybrid drive isn't unlike the system currently in use in much of Volkswagen's hybrid lineup, and while it's novel that the XL1 uses a 2-cylinder diesel powerplant as the fossil-fuel component, diesel hybrids are already starting to trickle onto European roads. The truly groundbreaking aspects of the XL1's running gear and body are expensive or nonsensical to mass produce, such as the car's carbon-fiber monocoque chassis or its magnesium wheels, but they do hint at the future of efficient motoring.

View Pictures:  2013 Volkswagen XL1

Carbon fiber — a key ingredient
Volkswagen uses carbon fiber and magnesium to make the XL1 a very light car; it tips the scales at just 1,753 pounds. While it's safe to expect that new cars will become lighter and lighter, the reasons that this hypermiler is so light cost many, many dollars. And while you may be able to build a 1,753-pound car in your garage, it's highly unlikely that you'd be able to build one with crash safety similar to that of the rest of the Volkswagen lineup.

The XL1 is built around a central carbon-fiber monocoque chassis, like you would find in a modern Formula One race car. The load-bearing cockpit is singlehandedly responsible for much of the car's rigidity, but the structure of the carbon molecules also allows for specific load paths in an accident, managing energy and keeping occupants out of harm's way.

Carbon-fiber monocoques are by no means inexpensive. Volkswagen won't tell us how much this one costs, but you can be sure it won't underlie a VW Golf any time soon. It's worth noting, though, that this carbon monocoque is made through a new, more efficient, resin transfer molding process, which allows for mass production and is more economical than the current, traditional process.

The entire monocoque weighs just 197 pounds and is attached to lightweight aluminum crash structures front and back. If nothing else, the bonding technology necessary to make the materials work together is sure to trickle down into production cars of the near future.

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Aerodynamically — and historically — advanced
The XL1 is also pretty darn aerodynamic. By that we mean that it is the most aerodynamic production car in the history of the automobile, but you probably could have guessed that by looking at the car's shape. What you might miss are all of the ingenious little reasons why it's so slippery. Take the e-mirrors, for instance. Aerodynamically optimized cameras on the XL1's flanks send pictures to LCD screens mounted on the inside of the doors — not far from where you're used to looking on a regular car.

There's no air intake at the front of the car; cooling air is pulled from the rear, where things are already turbulent. Air is sucked up through the engine bay and expelled out the top via a high-speed fan. The underbody is perfectly flat, and the 16-inch magnesium wheels and the tires are narrower than you'd believe, at just 115/80 up front and 145/55 in the back. With a drag coefficient of just 0.19, the XL1 can cruise at 60 mph while using just 8.3 horsepower. A GMC Yukon probably uses that much just to keep the air conditioning kicking on a hot day.

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