Volkswagen to bring 261-mpg car, carbon fiber technology to prime time

Two weeks ahead of the XL1's official launch at the Geneva Auto Show, Volkswagen announced last week that the super-green concept car is ready to shift into production.

With a staggering combined fuel economy rating of 261 mpg, the two-seater plug-in hybrid is claimed to be the most fuel-efficient production car in the world. It can run on electricity alone for 32 miles, then enjoys premium fuel efficiency thanks to its 47-horsepower, two-cylinder turbocharged direct-injection (TDI) diesel engine.

The XL1 also has a low center of gravity and exceptional aerodynamics. But arguably the crowning glory is the car's lightweight design. The body weighs 500 pounds and is made almost entirely from an incredibly light but strong carbon fiber-reinforced polymer.

"If you look at motor racing, the safest cars on the planet are race cars, and they're made from carbon fiber," said Mark Gillies, spokesman for Volkswagen. "If you went flying into a wall at 230 miles an hour, you're going to want to be doing it in carbon fiber rather than steel, because you'll live."

The XL1 brings that high-performance safety feature to the real world while also delivering sports car drivability, with a low center of gravity and acceleration from zero to 62 mph in 12.7 seconds. Its speed tops out at 99 mph.

It also completes the third evolutionary stage of Volkswagen's 1-liter car strategy. A decade ago, Ferdinand Piëch, chairman of Volkswagen's supervisory board, set out to make a practical car that would only need 1 liter of fuel to travel 62 miles. The XL1 makes that vision a reality.

Showcase for future technologies


But despite its innovative lightweight carbon fiber structure, the XL1's 261-mpg rating hardly seems possible. The 2012 all-electric Nissan Leaf, by comparison, has a combined U.S. EPA rating of 99 mpg.

Indeed, there are some factors the make the XL1's fuel economy figure especially high. For one, it is derived from the European Commission's rating system, which tends to produce more optimistic numbers than U.S. EPA's testing cycle. The XL1's rating is also inflated because it converts diesel's fuel efficiency gains into a gasoline miles-per-gallon equivalent.

That said, the XL1 still seems to hold the pole position in the green car race.

Volkswagen, Europe's largest carmaker, established a completely new handcrafted manufacturing process at its Osnabrück manufacturing facility to make the XL1's unique carbon fiber body. The automaker will initially produce a limited number of the cars destined for markets in Germany and Austria. So far, no pricing or exact production volumes have been announced.

"It is going to be niche. But it's going to show some of the technologies that are going to be coming in the next 10 to 15 years, particularly with materials and powertrains," said Gillies. "One of the key things about the future of the car is that they're going to get lighter, and the XL1 shows some of those technologies that will becoming into force."

The synergy in lightness

The XL1 is the primary example of what vehicle design needs to be in order to wean the transportation sector off oil, said Greg Rucks, transportation and industry consultant at the Rocky Mountain Institute.

"It demonstrates what an approach we call vehicle fitness is all about," he said. "Instead of starting with the engine and making the engine more efficient and thinking about the fuel and how you're going to deliver the energy, think about how to minimize the energy needed for propulsion in the first place."

The three key elements to improving vehicle fitness are to reduce rolling resistance, improve aerodynamics and reduce weight. Lightweighting is the most effective among them because of its "decompounding" effect, Rucks said.

When weight is removed from the body, the car can have a smaller powertrain and needs fewer batteries to power it. This further reduces the weight and enables the automakers to downsize the shocks and other weight critical components. "I'd say the XL1 is a great example of that," Rucks said.

Volkswagen was able to capitalize on all these savings by taking a "clean sheet" approach, which meant building the XL1 from the ground up over time. BMW did the same thing by designing an all-new vehicle architecture for its new i3 and i8 electric vehicles.

In making the passenger cabin of both vehicles primarily out of carbon fiber at its own carbon fiber production plant, BMW saved on the order of 1,000 pounds per vehicle over an all-steel structure, said Matthew Russell, BMW product and technology communications manager.

"[That] translates directly to range and efficiency and handling performance and acceleration and all of the things you want that we're trying to get out of electric cars," he said.

The i3 is a pure-electric vehicle with a 90-mile range that is expected to be in the price category of plug-in vehicles on the market today. The i8 is an electric-gasoline hybrid designed to get over 80 mpg but offer sports car performance, putting it in the north of the $100,000 price range. BMW will start making deliveries on the i3 this year and the i8 next year.

Japan and Germany lead in carbon fiber

The challenge for integrating carbon fiber into the mainstream vehicle market is that automakers aren't going to redesign their entire lineup using a new material the way BMW and Volkswagen have done, said Rucks. It would be far too expensive for the car company and the consumer. So the trick to seeing carbon fiber used in greater volumes is identifying specific auto parts that can be converted to carbon fiber at a price point that's comparable to steel.

Carbon fiber is much more expensive than traditional automotive materials, but there are cost-efficient manufacturing processes that can help bring the cost down to parity, he said. The high-strength, high-safety attributes of carbon fiber also offer tangible safety and convenience benefits that a customer might be willing to pay a small premium for. The hydraulics on the rear door of a hatchback would last longer without repairs, for instance, if the door itself were lighter. A light car saves drivers fuel, too.

Initially targeting high-value parts and producing them at scale multiplies the demand for automotive-grade carbon fiber, brings down the cost and paves a way for its use in more extensive applications, said Rucks.

So you move from smaller parts to bigger sub-assemblies, all the way to the entire vehicle, he said. "We think [that] offers a more viable pathway than jumping all at once to a clean-sheet design," Rucks said.

It also offers an opportunity to create jobs, he added. Japan and Germany are the current leaders in manufacturing the carbon fiber used today, but there are opportunities for U.S. companies to take the lead in making types of carbon fiber that are derived from bio-based instead of oil products that could ultimately be cheaper to produce.

"I do think there's no doubt that the growth of this industry could lead to a lot of new jobs, both in the raw materials portion of the supply chain and the production part of the supply chain," Rucks said.

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