First Drive: Volkswagen XL1 Plug-in Diesel Hybrid

By · June 26, 2013

VW XL1

Volkswagen XL1 in Wolfsburg, Germany. (Photo: Brad Berman)

A dozen years ago, Volkswagen embarked upon a project to design a vehicle that can travel 100 kilometers using merely one liter of diesel fuel. VW logically dubbed the car the L1. The company this week allowed a small group of American journalists to drive the fourth iteration of the car—this one known as the XL1—on a 40-minute trip near the company’s headquarters in Wolfsburg, Germany. I was part of the group that experienced the XL1’s iconoclastic blend of four efficiency strategies:

  • Plug-in hybrid power
  • Sleek aerodynamics
  • Severe light-weighting
  • Efficient (very) small diesel engine design

Combining these strategies has a multiplicative impact—allowing the XL1 to beat its 100-km goal by 10 percent, providing 110 kilometers on a single liter of fuel. (That equates to about 260 miles per gallon.) What's even more impressive is the XL1's design—a fun, stylish piece of automotive innovation that updates car coolness for the 21st century, swapping out horsepower and brawn as the measure of appeal and attraction, with an irresistible high-tech quirky charisma.

Gutsy, Eco, Chic

VW XL1 />

(Photo: Brad Berman)

The XL1 seats only a driver and a passenger to the side, staggered a few inches toward the rear of the car. The body design is wide in front, and tapers to much thinner proportions toward the back. While providing as much as 30 miles of all-electric capability from a 5.5-kilowatt-hour battery, stomping on the accelerator wakes up a 0.8 liter rear-mounted 48-horsepower engine—just enough internal combustion propulsion, combined with electricity, to move the car along with brisk city traffic or not feel left behind on Germany's famed highways. When that small diesel engine comes online, it loudly clatters, nearly directly into the passenger cabin. In an effort to save weight, sound dampening was ignored—making every flutter of the engine, as well as every bump in the road or scraping screech from the car’s ceramic brakes—a visceral experience.

This intrusion into the cabin is part of the car's gestalt, along with its scissor doors, side-view cameras (to replace mirrors), and futuristic shape. Power steering was also eschewed in the name of light weighting, making turns at any decent speed an athletic feat not dissimilar to steering a Tesla Roadster. It all adds up to a ton of fun. Efficiency is not a matter of sacrifice or anemia. VW made the XL1 gutsy and chic.

Even the tiny slot of a passenger window, manually wound up and down, felt analog-hipster. Of course, the small opening will make it impossible to ever receive a Supersized fast food meal at a drive-through window. Just as well—there’s absolutely zero chance this car will make its way to the United States.

Read My Lips: De-mon-stra-tion

Ulrich Hackenberg />

Volkswagen's Dr. Ulrich Hackenberg. (Photo: Brad Berman)

Volkswagen will use a manufacturing process that looks and smells a lot like mass production at its factory in Osnabruck, Germany—but merely 250 XL1 units will be made. Approximately the first 50 will be put on loan to VIPs for a few weeks at a time, or to Germany-based customers who submit proposals to demonstrate how the XL1 can be incorporated into a daily sustainable lifestyle. The first of those loaners have already been given out. Next, a “real” production run of 200 cars—that's right, just 200 cars—will be sold or leased like any other VW automobile. No pricing info is yet available.

In a meeting with the journalists, Dr. Ulrich Hackenberg, a chief product specialist on the Volkswagen board, yesterday repeated the word “demonstration” when speaking about the XL1. He also said that the company needed to invest in a full range of automotive technologies and fuels (from compressed natural gas and fuel cells to plug-in hybrids and, of course, diesels) to achieve corporate global efficiency targets. More importantly, Hackenberg said the use of 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—perhaps a subcompact like the Up city car it sells in Europe.

It’s too early to tell if a prospective future model will be made in greater quantities, or reach American shores. But for me, at this stage, it’s enough to know that the slick head-turning ultra-lightweight XL1 exists—and can serve as a compelling vision for quantum leaps in aerodynamics and high-tech appeal. The Cd of the XL1 is a super-slippery 0.19. It weighs only 1,753 pounds, by virtue of its carbon-fiber body.

VW XL1

The car’s plug-in hybrid system consists of a 48-horsepower two-cylinder diesel engine, a 27-horsepower electric motor, a seven-speed DSG dual-clutch automatic transmission, and a lithium-ion battery. This design is now in VW’s back pocket, ready to be used if regulations demand, or brought forward in some partial form or fashion to a future VW electro-diesel model. And it's ready to be emulated by any car company with a brave vision.

Smooth Sailing

Speed is not the XL1’s raison d’etre. It has a top speed of 99 miles per hour, but accelerates from 0 to 62 mph in a leisurely 12.7 seconds. After hitting highway speeds, take your foot entirely off the accelerator—and there’s absolutely no regenerative braking. That’s what VW product people call sailing.

With the slightest depression of the brake pedal, the regen braking comes back into action—feeding braking energy into the liquid-cooled lithium ion battery pack. If you find the sweet spot on the accelerator pedal—just barely into the throttle—the driver can simultaneously maintain highway speed, while producing some level of regen—essentially converting diesel fuel into battery power on the fly from this parallel hybrid system. The press release for the car reads: “This super-efficient Volkswagen can cruise at a constant 62 mph while using just 8.3 horsepower.”

VW XL1

To save weight and improve aerodynamics, VW engineers removed side-view mirrors. Instead, they used low-profile cameras and a monitor inserted into the door.

I only had a half-hour in the car, so there wasn’t enough time to fully play with how to wring the greatest efficiency and driving pleasure out of the system. But what I did experience was a blast, albeit mildly compromised by the car’s lack of good visibility. I’m 6’ 4”—so street signs above the road were hard to see, no matter how I tilted the driver’s seat. The side view monitors—while in all likelihood very faithful to what you would see in an analog side mirror—were hard to trust. I kept trying to peer over my shoulder, but the camera provides the only unobstructed view for checking if it's safe to move into adjacent lanes.

Leading the Way

After my relatively brief drive of the XL1, I returned to VW’s Autostadt car theme park and history museum. There, on display, were two previous versions of the XL1, one from 2002 and another from 2009. While those previous L1 prototypes are cool—in a Batmobile way—this latest XL1 I drove felt much more like a real and practical form of city mobility, complete with side-by-side passenger comfort and enough cargo space for two pieces of carry-on luggage.

VW XL1

Okay, so it won’t be coming to the U.S. and won’t be produced beyond 250 models. VW is not hiding that fact—as opposed to some of its competitors that pass off their limited-run plug-in models as “production” vehicles, but make merely enough to exactly comply with regulations.

All of the technologies found in the XL1 are ready-for-primetime, even if it isn’t exactly economical to throw all of them together in one car, as VW has done. Nonetheless, the XL1 can be shown off as an impressive vision of what’s possible when great aerodynamics, lightweight design, and plug-in diesel technology are integrated.

At the same time, I can't forget what VW’s chief of electric technology Dr. Rudolf Krebs told me earlier this year. “We want to become the leader in electrification,” he said. Then he flashed a slide that showed seven plug-in hybrids and two pure EVs in VW’s product roadmap in the next two years. If any smidgen of quirky geeky excitement from the XL1 finds its way to those cars, Volkswagen could shake up the world of electrified vehicles with a fresh alternative to ultra-efficient travel.

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