The development of the “1-liter” car was started by Volkswagen in 2002 with the first L1 prototype, evolved in to the L1 and XL1 concept cars presented in 2009 and 2011 and now has finally arrived to the production-ready XL1 which will make its debut at the 2013 Geneva Motor Show.
While the driver and passenger sat in a tandem arrangement for optimal aerodynamics in the L1 concept car presented in 2002 and in 2009, in the XL1 two occupants sit slightly offset, side by side, nearly as in a conventional vehicle.
The XL1 is equipped with a plug-in hybrid system featuring a two-cylinder TDI engine (35 kW/48 PS), a 20 kW/27 PS electric motor, a 7-speed dual clutch gearbox (DSG) and a lithium-ion battery.
This result was achieved thanks to the extremely low weight (795 kg), the optimal aerodynamics (Cd 0.189) and a low centre of gravity (1,153 mm high).
This gives the XL1 the ability to cruise on the road at a constant speed of 100 km/h using just 6.2 kW/8.4 PS, with just 21 g/km of CO2 emissions.
In all-electric mode, the XL1 requires less than 0.1 kWh to cover a driving distance of over one km and has a range of up to 50 km.
The top speed is electronically limited to 160 km/ h and the acceleration from 0 to 100 km/h takes 12.7 seconds.
Visually, the XL1 also adopts the styling lines of the L1 presented in 2009. However, the XL1 has a more dynamic appearance thanks to its greater width.
The XL1 is 3,888 mm long, 1,665 mm wide and just 1,153 mm tall which means that its length and width are comparable to those of a Polo, but sits 129 mm lower than a Porsche Boxster.
The body design was uncompromisingly subjected to the laws of aerodynamics. At the front, the XL1 exhibits the greatest width; the car then narrows towards the rear. Viewed from above, the form of the XL1 resembles that of a dolphin; especially at the rear, where the lines optimally conform to the air flow over the car body to reduce the Volkswagen’s aerodynamic drag.
The wing doors are hinged at two points: low on the A-pillars and just above the windscreen in the roof frame, so they do not just swivel upwards, but slightly forwards as well.
The doors also extend far into the roof. When they are opened, they create a large amount of entry and exit space.
In side profile, the roofline traces an arc from the A-pillar back to the rear.
The rear wheels are fully covered to prevent air turbulence; the air flows here are also optimized by small spoilers in front of and behind the wheels. Observers will look for door mirrors in vain; replacing them are small cameras integrated in the wing doors known as e-Mirrors (digital outside mirrors) that send images of the surroundings behind the car to two displays inside the vehicle.
The front of the XL1 no longer exhibits the typical radiator grille; however, it still reflects the styling of the current Volkswagen “design DNA” with a predominance of horizontal lines. Specifically, there is a black cross-stripe that combines with the energy-efficient dual LED headlights to form a continuous band.
The actual air intake for cooling the TDI engine, battery and interior is located in the lower front end section and has electrically controlled louvres. The narrow turn indicators are also designed in LED technology; these form an “L” shape which vertically follows the wheel housing and horizontally a line beneath the headlights.
This creates a front end, which – although it is completely redesigned and extreme in its dimensions – can immediately be recognized as a Volkswagen design by its clean lines.
At the rear, however, the design takes an entirely new path, but the brand values of precision and quality are clearly evident.
The XL1 represents a new dimension of Volkswagen design. Four characteristics are discernible: First, there is the characteristic dolphin body form, once again, that narrows towards the rear with very precise trailing edges for perfect aerodynamics. Second, there is the coupé-shaped roofline without rear windscreen.
Merging into the roofline is the large rear boot lid that covers the drive unit and 120-liter luggage space. Third, there is a strip of red LEDs that frames the rear section at the top and on the sides. Integrated in this LED strip are the reversing lights, rear lights, rear fog lights and brake lights. Fourth, is a black diffuser, which exhibits nearly seamless transitions to the completely covered underbody.
The body of new XL1 weighs just 230 kg and is based on a monocoque frame. Both the outer panels and the structure are produced from lightweight CFRP using the RTM process (Resin Transfer Moulding).
The density of this material or its specific gravity is only around 20 per cent that of a comparable steel exterior skin: the exterior panels of the XL1 are just 1.2 mm thick.
Compared to other methods such as manufacturing CFRP in a prepreg process, CFRP production via RTM is more economical − with lower costs at higher part volumes − because it can be automated. The RTM parts are produced in multi-shell, heated and vacuum-sealed tools. This involves injecting liquid resin at high pressure into the tool containing the semi-finished carbon material whose interior has the shape of the part to be produced. The part cures afterwards in the mould.
The XL1 is manufactured by Volkswagen Osnabrück GmbH. In the former Karmann plants there, around 1,800 employees produce such cars as the Golf Cabriolet and the new Porsche Boxster.