Volkswagen has been evolving its superefficient-vehicle concept since the 1-Litre car debuted in 2002, and the XL1 concept is the most recent variation on that theme. Although many specifications are close to what we saw in the 2009 L1 concept, the XL1 is more efficient, more practical, and closer to reaching production.
Volkswagen is relying on new carbon-fiber and aerodynamic developments to bring fuel economy below the targeted 1.0 liter per 100 kilometer mark, which is equivalent to 235 mpg. The XL1 allegedly averages 261 mpg (0.9 liter per 100 km) and travels up to 21.7 miles on a full charge of its lithium-ion batteries before kicking on the 0.8-liter turbo-diesel engine. Volkswagen sandwiches the hybrid module between the diesel engine and seven-speed dual-clutch automatic, which allows the electric motor to bump-start the diesel while the vehicle is moving. Unlike the L1 concept, which was front-wheel drive, the XL1 has a rear-mounted engine and rear-drive.
The two-cylinder diesel is, essentially, half of a 1.6-liter TDI engine used in everything from the Golf to the Passat. That means the engine uses all the latest technology and meets Euro 6 emissions requirements, which should translate into a cost-efficient path to production for the XL1. Less than a liter of displacement results in 47 hp and 89 lb-ft of torque for the TDI engine. The electric motor produces a maximum of 27 hp and 74 lb-ft of torque. With the engine and motor working together, the maximum torque output is 103 lb-ft.
Performance figures for the XL1 are very respectable given the claimed 261-mpg fuel economy. A jaunt to 62.1 mph should require about 11.9 seconds, and cruising at that speed requires only 8.3 hp. For reference, a Golf 1.6 TDI requires almost 18 hp to maintain a 62-mph cruising speed. With a top speed of approximately 100 mph, the XL1 is fast enough to survive a trip on congested highways, although the fuel economy would undoubtedly suffer at such extreme speeds.