Presented this week at the 2011 Qatar Motor Show, the Volkswagen XL1 provides a look at VW's latest thinking in the realm of mileage-maxing transport. Representing a third evolutionary stage in the automaker's longstanding "1.0-liter strategy" of creating a production vehicle that would be practical for daily use and travel over 100 kilometers on a single liter of fuel, the two-seat XL1 plug-in hybrid lays claim to being the most efficient car in the world.
The Volkswagen XL1 is powered by an 800cc/48-horsepower two-cylinder turbodiesel engine that uses the same basic technology as VW's current 1.6-liter/inline-four TDI. It's paired with a 27-horse electric motor energized by a lithium-ion battery pack. The primary electric components of this team are located just above the rear axle with the motor itself sandwiched between the TDI engine and a seven-speed DSG dual-clutch transmission. VW says the XL1 Concept can accelerate from 0-62 mph in 11.9 seconds and has an electronically limited top speed of 100 mph. A true dual-mode hybrid, the XL1 Concept also can travel up to 22 miles on pure electric power and/or selectively apply EV assist to supplement the diesel engine. In addition to on-the-fly range extension capabilities using its regenerative braking system, the car's 2.6-gallon fuel tank allows it to run a combined 342 miles before needing a complete recharge/refill.
Light makes it right
A key part of the Volkswagen XL1's operating efficiency lies in its lightweight, wind-cheating design. Extensive use of carbon-fiber reinforced plastic (CFRP) in the bodywork and monocoque structure coupled with low-mass aluminum suspension bits make up over 75 percent of the entire XL1 package and keep curb weight to a mere 1,753 pounds. Shaped like a stylized dolphin and offering side-by-side instead of the tandem configuration seen in its two predecessors, the XL1's aero stats are simply stunning: a 0.186 coefficient of drag. Access to its cabin is simplified by a pair of lift-up demi-gullwing doors but those aboard will need to travel light, as the rear trunk area offers a decidedly modest 3.5 cu-ft of luggage space.
Mechanically the XL1 features a variety of efficiency-enhancing components from its polycarbonate front and side glass to low-draw LED head and tail lamps to CFRP anti-roll bars, ceramic brake discs and magnesium wheels that mount a new generation of Michelin low-rolling resistance tires -- 115/80R15s up front and 145/55R16s in the rear, discreetly tucked away behind full wheel skirts. As expected, the XL1 also is fitted with electronic stability control and anti-lock brakes to complement its fully-crash engineered passenger safety cell.
While offering no time window as to when a variation on the XL1 theme may turn up in a showroom, Volkswagen did say that the existence of this kind of prototype "demonstrates that the goal is now within reach."