Volkswagen has revealed a diesel hybrid concept that can deliver well in excess of 300mpg. The new car, called the XL1, is the third concept built by the company to be capable of traveling 100km (62 miles) on a single liter of fuel. The first two vehicles, introduced in 2002 and 2009, used tandem seating, but the XL1 achieves the goal (or at 0.9l/100km, surpasses it) while looking remarkably conventional.
Officially introduced today at the Qatar auto show, the XL1 is powered by an 800cc, two-cylinder turbodiesel powerplant (half a BlueMotion engine), producing 47hp. It's supported by a 27hp electric motor that is fueled by lithium-ion batteries. These can be charged from a domestic plug, allowing the car to travel for 35km (22 miles) on electric power alone.
The electric motor can also be used to support the diesel engine's torque during "full power" acceleration, lifting the figure from 74lb-ft to 103lb-ft. But it also contributes to overall efficiency that's well beyond that of regular production cars. The XL1 requires just 8hp to maintain a constant speed of 62mph; by contrast, a Golf 1.6 TDI requires 18hp to achieve the same feat.
The result is a car that can return 313.9mpg while being capable of a top speed of 100mph (electronically limited) and a 0-62mph time of 11.9sec. Despite having a relatively small 10-liter tank for diesel, the XL1 has a range of around 340 miles.
The XL1 uses a carbon fiber-reinforced polymer (CFRP) monocoque construction, helping it to weigh just 1,753lbs. Of this, 500lbs is taken up by the drive unit, 337lbs the running gear, 176lbs equipment (including seats) and 232lbs of electrics. The body is the final 507lbs.
The car's styling is more "normal" than VW's previous one-liter concepts, although it's clearly designed for efficiency. It's shorter than a Polo, but lower than a Lamborghini Gallardo, at 45.5in. The profile is not unlike Honda's original Insight. But the XL1's drag coefficient is just 0.186.
The concept is not destined for direct production. But parts of its hybrid powertrain could be used on the next generation of eco models. The matter is said to have been the subject of intense debate within the VW Group in recent months, with VW itself favoring a stronger push toward diesel hybrids and Audi flagging up its Wankel-based range-extender technology.