First Drive: The 260-MPG Volkswagen XL1 Plug-in Diesel Hybrid


Quantum leaps in automotive efficiency are often said to be just around the corner—only pending an imminent breakthrough in battery technology…or the discovery of an enzyme for making biofuel…or the development of a new economic model for hydrogen distribution. But the sleek two-seat car I drove yesterday—which can travel 110 kilometers on a single liter of diesel fuel—does not rely on any single laboratory ah-ha moment. Instead, the Volkswagen XL1 achieves its astounding 260-mpg efficiency with an all-of-the-above tech approach, combining a portfolio of on-the-shelf technologies into a single vehicle platform.

I was among a small group of American journalists that VW this week allowed to drive its crazy-cool XL1 lightweight aerodynamic diesel plug-in hybrid. That’s a mouth full, so let’s break down the XL1’s four main characteristics.

Lightweight: The two-seater XL1 is just 153.1 inches long, 65.6 inches wide, and a modest 45.4 inches tall. Its core construction is made up of carbon fiber. The creature comforts we have come to expect—in the areas of a quiet cabin, power steering and electric controls of locks and doors—have been eschewed in favor of weight reductions. The XL1 weighs in at a mere 1,753 pounds.

Aerodynamics: The measure of slippery-ness in the auto industry is drag—and the XL1’s coefficient of drag is an ultra-low 0.19. The car is much wider in front, and tapers to a narrow tail. The passenger seat, next to driver, sits back staggered a few inches. (Previous L1 prototypes put the passenger directly behind the driver.) Anything that prevents the car from slicing through wind has been removed—including the side-view mirrors, which have been replaced by tiny cameras (built into side panels) that display an image of the adjacent lane in a monitor built into the door. The combination of low weight and great aerodynamics means the XL1 can cruise at a constant 62 miles per hour while using just 8.3 horsepower.

Clean diesel: Volkswagen is a world leader in efficient clean diesel vehicles. Today’s diesels are quiet and, due to its strong axle-twisting torque characteristics, are fun to drive. Instead of employing diesel benefits to provide more power, VW downsizes the engine in the XL1 to two-cylinders, 0.8 liters and 48 horsepower. Yet, because the car is so light and slippery, it never feels underpowered—and steers well despite no power steering.

Plug-in hybrid: Like diesel, electric powertrains are efficient and powerful from a standstill. The 27-horsepower electric motor, receiving energy from a 5.5 kilowatt-hour lithium ion battery pack, can operate the two-seater purely on electricity with no emissions for about 30 miles. But it’s a parallel hybrid that can call upon both diesel and electricity to provide sufficient power for quick acceleration or highway speeds. A battery of the XL1’s size usually takes less than two hours to fully charge from a 240-volt supply.

All four of these strategies are in the marketplace now. That’s not the news. What’s novel here is the combination and integration of the four approaches into a head-turning sleek design, complete with wing-like scissor doors that gives this vehicle it’s eco-geek chic. It’s a car that even the most ardent horsepower-hungry gearhead can admire—even though its zero-to-60-kilometer pace is a leisurely 12.7 seconds. Its coolness transcends all conventional metrics.

Of course, when you add up the cost of all these technologies, it’s hard to make an economic case for mass production of the XL1. Yet, VW has green-lighted a small production run of 250 vehicles for the European market. The first units have already been put on temporary loan to VIPs and celebs to begin evaluation.

Sorry, VW has no plans to bring any of those units to the United States. But Dr. Ulrich Hackenberg, a chief product specialist on the Volkswagen board, hinted that a very small diesel engine, like the XL1’s two cylinder 830cc TDI Clean Diesel, combined with a parallel plug-in hybrid layout, could soon be applied to another VW model—although it’s likely to be in a European subcompact like the VW Up. Most importantly, VW has created a vision of what plug-in diesel hybrid technology can achieve: a car that’s beautiful, fun to drive, and provides a revolutionary leap in fuel efficiency.

Article by Brad Berman, appearing courtesy ebay Green Driving.



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