News.

L1 Concept is driven by new high-tech TDI and E-motor
Carbon fibre reinforced body of the L1 weighs just 124 kilograms
Maximum speed 160 km/h; L1 consumes just 1.49 litres diesel per 100 km
CO2 emissions reduced to a new best value with just 39 g/km

Wolfsburg/Frankfurt, 16 September 2009 - Technological breakthrough for the 1-litre fuel consumption car: International Motor Show (IAA), Volkswagen is presenting the concept of the future L1 in a world premiere that points the way toward the production version. The full hybrid vehicle weighs just 380 kilograms thanks to its carbon-fibre reinforced body (CFRB). With a combined fuel consumption figure of 1.49 litres of diesel per 100 kilometres, this fully road-ready and extremely aerodynamic (Cd 0.195!), Volkswagen is intended to become the most fuel-efficient automobile in the world. CO2 emissions of the 160 km/h L1 are similarly low at 39 g/km.


Retrospective: Seven years ago, Dr. Ferdinand Piëch, at that time Chairman of the Board of Management and today Chairman of the Supervisory Board of the Volkswagen Group, drove a prototype from Wolfsburg to Hamburg that was unlike any other car before it: the Volkswagen 1L – the world’s first car with fuel consumption of one litre fuel per 100 kilometres. The man and machine wrote automotive history. In April 2002, however, it was also clear that the time for a production version of the 1L lay far in the future. Production of the body itself – from carbon-fibre reinforced plastic (CFRP) – was not realistic due to cost considerations. By 2009 the time had come: Volkswagen is making a clear statement at the IAA in Frankfurt with the second generation of this ingenious car: The L1 represents a step forward into the future with completely new technology and a new design; revolutionary yet close to production readiness.

“It is an enormous challenge to control costs in producing the monocoque out of CFRP,” says Dr. Ulrich Hackenberg, member of the Board of Management for the Volkswagen Brand with responsibility for development. Both technically and visually, the CFRP body is already considered a significant achievement in car design. Unique on this car are the proportions of its dimensions. While the length of the L1 at 3,813 millimetres is still similar to that of a Volkswagen Fox, and its height is 1,143 millimetres, the car’s aerodynamically optimised width (1,200 millimetres) has no comparisons in the world of today’s production cars.

The seat layout fitting the design goal of the L1 was dictated by the uncompromising aerodynamic form of a glider: One seat behind the other. Entry to the concept car is also similar to that of a glider; through a roof cover hinged at the side. On this second generation of the L1, the concept has been further honed; each component has been redesigned, a special chassis with aluminium components was developed, and above all the crucial CFRP technology from Formula-1 racing and airplane construction was transferred to automotive manufacturing. This has been combined with a unique form of hybrid drive to create a near-production vehicle. 2013 is the target year for this future dream to become a reality.

The TDI, E-motor and 7-speed DSG are located at the rear, and they combine to create the most fuel efficient road-legal car hybrid drive in the world. Proof of this are its 1.49 litre per 100 kilometres fuel consumption and 39 g/km CO2 emissions. Serving as the primary drive source is a completely redeveloped two-cylinder turbo-diesel with common rail direct injection (TDI). It is operated in two different modes depending on the load conditions. In the standard “ECO” mode, the 800 cm3 TDI develops a power of 20 kW/ 27 hp (at 4,000 rpm); in “Sport” mode the car’s power rises to 29 hp / 39 kW (at 4,000 rpm). The TDI’s maximum torque is 100 Newton-meter (at 1,900 rpm).

The hybrid module has been integrated into the housing of the 7-speed DSG (Direct Shift Gearbox). It is located between the TDI engine and the DSG gearbox and consists of a 10 kW / 14 hp electric motor and a clutch. The E-motor is supplied with energy from a lithium-ion battery located at the front of the car.

In normal operation the electric motor can support the TDI engine in conditions such as by electronic load point shifting and in acceleration. Restarting the TDI is a very easy process. In so-called “pulse starting” of the TDI, the electric motor is sped up and is then coupled to the TDI unit to provide almost instant starting. The entire process takes place automatically and without jolts, so the driver hardly notices the restarting of the TDI engine.

In braking phases, the E-motor operates as a generator to charge the lithium-ion battery by recovering braking energy. The gears of the automatically shifting DSG are always selected with the aim of achieving the best possible fuel economy. The engine controller regulates all energy flow and drive management tasks taking into account the moment by moment demands for power made by the driver.

The TDI engine in the L1 is a new development. Yet, even here Volkswagen has been able to exploit synergies to design an engine that is both innovative and cost-effective. Hence, this 0.8 litre TDI unit has been derived from the 1.6 TDI just introduced a few months ago.

Gear shifting work aboard the L1 is handled by the 7-speed DSG, which is one of the most innovative automatic transmissions in production. Compared to the version equipping the new Polo, for example, the design of the Direct Shift Gearbox has been developed to include clutch control for the hybrid module. Furthermore, individual gear ratios have been optimised to attain responsive driving performance despite the car’s extremely low fuel consumption.

The L1, equipped with ABS and ESP, has a top speed of up to 160 km/h – this is remarkable considering its fuel efficiency. With maximum acceleration from a standstill, the two-seater reaches 100 km/h after just 14.3 seconds. The fuel tank holds just ten litres yet, this is sufficient for a theoretical driving range of about 670 kilometres, given the car’s 1.49 litre average fuel consumption.

The driver and passenger sit one behind the other. At both locations, the seat position is ergonomically ideal and very comfortable. All instruments and controls are arranged over a 180 degree radius for the driver, which places them perfectly within view and reach. The instrument panel itself has been integrated into the monocoque and is made of CFRP. The interior applications are produced from carbon fibre reinforced plastic (GRP).

To start the L1, the driver pushes a button on the right side of the steering wheel. When it is rotated, the round start button simultaneously serves as a gear selector switch and is used to activate the electronic handbrake (Drive, Neutral, Reverse and Park). The entry canopy and rear hatch are opened electrically by touch controls to the left and right of the driver. Also designed as touch sensors are controls for the entire air conditioning control system. Via multifunctional keys in the steering wheel, the driver controls the on-board computer, navigation and entertainment systems.

The classic door mirror and rear-view mirror have been completely eliminated on the L1. In their place, cameras display images on an OLED-active (OLED = organic light emitting diode) display that serves as a central instrument in front of the steering wheel. A Park Distance Control (PDC) system makes parking easier as well.
In case of a crash, not only are the driver and passenger protected by the monocoque, which is designed as a highly rigid CFRP safety cell, as well as aluminium crash elements in the front of the car, but also by a steering wheel airbag and head/side curtain airbags to the left and right inside the entry canopy.

The two-seat monocoque, including the tubular frame driver’s seat and passenger seat as well as the exterior body skin, all consists of CFRP. There are no doors. Instead, the driver and passenger climb into the L1 from the top. An electrically actuated entry canopy is opened above the seats for this purpose. Closing is made easier by a pull assist feature. Headlights and taillights all utilize LED technology, which consumes less energy. The rear wheels are completely covered; their wheel covers can be removed to change the tires. The underbody is also completely enclosed. The 0.8 TDI is cooled via lateral air channels integrated in the body. These automatically open and close based on the hybrid unit’s operating state and vehicle speed. The tailgate is opened in the usual, manual way. It too consists of CFRP. Inside is a stowage space of 50 litres.

Carbon fibre reinforced plastic, as the name implies, consists of multiple layers of high-strength carbon fibres, which are integrated in a very tough matrix. This mix results in an extremely strong and lightweight composite material. Now Volkswagen has succeeded in finding a production-viable and cost-effective way to produce CFRP parts in suitable volumes.

The reason that CFRP is the ideal material for the L1 body is demonstrated by considering its weight and strength. The L1 weighs just 380 kilograms. Of the 380 kilograms curb weight, 122 kilograms are taken by the drivetrain, 79 kilograms by the chassis, 35 kilograms by interior furnishings and 20 kilograms by the electrical system. 124 kilograms remain, and this is precisely the weight of the body.

And there are other advantages: the material’s extremely high stress limits and its ideal forming properties for even the most challenging of design features.

The design and styling of the L1 – function and form – join to provide one uncompromising unit. Walter de Silva, Head of Design for the Volkswagen Group has this to say: “The design of the L1 redefines classic and aesthetic vehicle traits. Especially significant, of course, is how the nearly rocket-shaped lines catch one’s attention. All of its moving parts are integrated so accurately that the body resembles a rocket or jet. It is a body that cuts through the air with minimal aero dynamic resistance.”

The Head of Group Design continues: “In a sense, we applied the same principle to the front end of the Scirocco, where the headlights are joined by a glossy black stripe, and the brand logo is also placed on the engine bonnet. This underscores the sporty character of this automobile.”

The extremely aerodynamic design also shapes the rear with its diffuser and wheels that are completely enclosed. The most distinctive feature of the overall appearance in the rear are the LED taillights that were worked into the TDI’s air intake ports. De Silva: “Another identifying feature is the air intake directly behind the cockpit – a nearly abstract, graphic element that underscores the purposeful aesthetics of this vehicle.” Due to the driver’s low seating position, there is an additional window in the roof that is ideal, for example, to view traffic lights.