There was a familiar feel to the biggest star of the Volkswagen stand at the 2009 Frankfurt Motor Show. The L1, a vehicle with tandem seating that Volkswagen introduced at the German show, bore more than a passing resemblance to the "1-liter" car revealed in 2002.
Described by Volkswagen’s head of research and development, Ulrich Hackenburg, as a “technology carrier,” the L1 is powered by an 800-cm³ diesel engine, has a mass of just 380 kg (838 lb), and is capable of achieving fuel economy figures of 189 mpg. The two-cylinder engine is derived from 1.6-L TDi BlueMotion unit and has 29 bhp (22 kW) and 74 lb·ft (100 N·m). The 10-L (2.6-gal) tank can achieve a range of 670 km (416 mi), while the CO2 output figure has been quoted as 39 g/km.
An electric motor works alongside the diesel engine, assisting acceleration and with the ability to operate as a standalone powerplant. Under normal conditions, the 10-kW motor remains redundant, but bursts into life when extra acceleration is required, boosting torque by 40%. The motor also has the ability to run the car by itself for very short distances.
With an emphasis on efficiency and aerodynamics, side-hinged, electrically operated doors are used, helping to achieve an aerodynamic drag coefficient (Cd) of 0.195. Weight is saved by using aluminum and carbon fiber on the body, and reinforced plastic on the safety cell, which weighs just 124 kg (273 lb).
Tandem seating is the main reason that such high fuel economy figures can be achieved. Once inside, passengers are seated in carbon seats with extra thin but strong casings. The interior is much changed from the standard range of production Volkswagen vehicles. Out goes the rearview mirror, replaced by an organic LED, and the traditional vehicle controls are situated around the steering wheel.
Despite the use of a diesel-electric hybrid on the L1, the success of TSI and TDI internal combustion engines means that Hackenburg and his team cannot ignore conventional powertrains in its future product lineup. Efficiency, he says, as well as downsizing, are the way to evolve diesels and gasoline units.
“If you look purely to thermoelectric developments, we will see more technology in the engine, from camshift controllers to cylinder deactiviation,” said Hackenburg. “But, in combination with electrification of the engine, there is another option for items such as oil pumps to be electric. We will increase efficiency of the engines to the very highest level."
The future of Volkswagen range of six- and eight-cylinder engines is less assured: “There is a trend going from vee engines to four cylinders by using TSI technology,” he said. “Performance-wide it is possible, there is a question about premium cars, so it will probably be easier the alter the Volkswagen range, than, say Audi's. I think the trend will be greater from V8 to V6, rather than V6 to four-cylinder, with hybrid technology being involved, too."
One area that isn’t quite so active is fuel cells, but Hackenburg is wary to ignore them completely. “We are still developing them, but it is not a priority in terms of vehicle technology. We want to be ready when fuel cells come, but it will take a long time because of hydrogen storage and transportation issues and a lot of questions need to be solved.”