With its shapely sheetmetal, usable cabin, and production intent, the 261-mpg Volkswagen XL1 seems too good to be true. But to believe in the Volkswagen XL1, you simply have to recognize that the Bugatti Veyron exists. Both cars are pet projects of Dr. Ferdinand Piech, the authoritative chairman of the Volkswagen Group’s supervisory board who is drawn to extreme cars. And after delivering a 260-mph supercar, Piech is now set on building a 260-mpg ecocar. While a hyper-efficient two-seater may not be as sexy as a Veyron and could never command its $1.7-million price, the engineering and ingenuity behind the XL1 is just as impressive as that which went into the Bugatti.
The XL1’s genesis is a program started in 1999 with the goal to develop a production car that consumes less than one liter of fuel for every 100 kilometers driven, or about 235 mpg. To prove such fuel economy was possible, Piech revealed the first concept to the public during a Wolfsburg-to-Hamburg drive in 2002. Then, in 2009, Volkswagen introduced a significantly updated car at the Frankfurt auto show known as the L1 concept. But both those early prototypes were impractically small and narrow, with a passenger seated behind the driver.
Now, Volkswagen has delivered a third interpretation of the one-liter car and, having driven it, we can say that the XL1 is seriously close to production readiness. In fact, the German automaker is committing to limited production in 2013.
Svelte, slippery, and slow
To achieve the remarkable 261 mpg (on the European fuel economy cycle), Volkswagen uses an electric drivetrain and a 0.8-liter two-cylinder diesel. The lithium-ion battery pack is good for nearly 22 miles of electric driving before switching to diesel power. Volkswagen doesn’t use the diesel engine to generate electricity like the Chevy Volt’s gas engine does. Instead, it directly drives the rear wheels because it’s more energy efficient to do so. No matter which power source the car is using, though, the XL1 uses all seven gears of the dual-clutch automatic transmission, a significant departure from the usual continuously variable transmissions and single-speed gearboxes of hybrids and EVs. A full recharge of the battery takes about one hour and 15 minutes from a 220-volt power source.
The diesel engine makes just 47 hp and the electric motor only 27 hp, so Volkswagen invested a significant amount of time reducing weight and minimizing aerodynamic drag. To cut down on frontal area, the passenger seat is staggered to sit slightly behind the driver’s seat. This allows the car to be just 65.2 inches wide — a bit smaller than a Volkswagen Polo — yet not feel too cramped. The length is also similar to that of a subcompact car, but the 45.5-inch height is typically reserved for supercars. Thanks to the teardrop-like shape, Volkswagen is claiming the world’s most aerodynamic shape with the slippery 0.186 drag coefficient. A Toyota Prius, for comparison, has a coefficient of drag of 0.25. The XL1’s combination of a small frontal area and minimal drag means it takes just 8.3 hp to cruise at 62 mph. That’s less than half the power required to move a Volkswagen Golf with a 1.6-liter diesel.
The weight watching was so methodical that some of the wiring is aluminum rather than copper to save a few ounces here and there and the wheels are magnesium to lower the rotational mass. Those little details are neat, but Volkswagen’s real breakthrough is a carbon-fiber tub that will theoretically be cost effective for a production car. We doubt the production run will be huge, but even bringing a few thousand XL1s to market with this technology and construction would be an impressive feat. We were assured the car meets all safety regulations (at least in Europe) as it sits now. Though the passenger doesn’t need an airbag because the seat sits too far away from the dash, we imagine potential customers would demand another airbag. Expect a slight increase from the 1753-pound curb weight when the car comes to production, but rest assured the engineers are sweating every ounce.
Completely competent, but not without compromise
Getting into the XL1 isn’t terribly easy. The gull-wing doors and wide sills that would be standard for a supercar feel a bit out of place in this eco-mobile. Once you manage to wiggle into the carbon-fiber bucket seat, it’s surprisingly comfortable and supportive. Push the start button once to arm the various vehicle systems and then a second time to turn everything on. Assuming the battery is charged, you’ll quietly glide away in electric mode. The sideview mirrors have been replaced with cameras, but the displays in each door are placed a few inches too low to feel comfortable checking them. Thankfully, the screens offer a crisp picture because this prototype car is worth a lot of money and we’re driving it on the streets of Doha, Qatar where every SUV seems to be taking part in a time trial.
We need to use quite a bit of accelerator to keep up with our convoy since the CC and Touaregs each have at least twice as many cylinders as we do. Sprinting from 0-62 mph isn’t exactly what the XL1 was designed for, but the 11.9 seconds required to do so feels adequate for real roads with traffic. During hard acceleration in EV mode, the diesel engine will kick on to provide additional thrust. Volkswagen sees this as a safety feature because the electric motor only produces 74 lb-ft of torque and the total output can be as high as 103 lb-ft of torque with the diesel engine assisting. There’s quite a bit of noise from the tiny diesel when you’re on the throttle, but it’s strangely satisfying to hear the diesel rev because it confirms VW’s commitment to stripping out non-essential weight, which is sound-deadening material in this case.
Roundabouts are popular in Qatar and they provide a good opportunity to show off the XL1’s precise manual steering. With skinny Michelin tires that are optimized to provide the least amount of rolling resistance, the steering doesn’t need any power assist. The ceramic brakes also lack power assist and they feel a little disconcerting at first. If the XL1 is going to come to America, it’ll need to have power brakes to be accepted by the general public. Otherwise, the car drives just like you’d imagine. Most concept cars we drive feel as if they are made of hopes and dreams and might stop working any minute, but the XL1 felt sturdy enough to drive back to Wolfsburg on its own power.
Mpg is the new mph
Despite the small market for an expensive subcompact car that will probably never pay for itself in terms of fuel savings, Volkswagen is committed to bringing the XL1 to production by 2013. We’re likely to see the engine become a direction-injected, turbocharged gasoline burner for cost reasons, but the one-liter target will still be met and the rest of the car is expected to be very similar to the XL1. Engineers in Wolfsburg are currently trying to iron out the remaining safety, drivetrain, and driver comfort concerns without adding too much weight or cost. Given Piëch’s passion for the car, though, we are confident Volkswagen will be able to bring a limited number of XL1s to market within a few years. It looks like 261 mpg is the new 260 mph.