2011 Volkswagen XL1 Concept

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Powering the XL1 is a compact 800 cc TDI two-cylinder common rail diesel engine developing 47 hp. It's linked to an electric motor producing 27 hp, resulting in a total of 74 hp - a modest output yet more than enough when the low kerb weight of 1753 lbs (795 kg) of the vehicle is taken into account.

The TDI engine is linked to an electric motor and a seven-speed DSG gearbox with an automatic clutch mounted between each unit. The electric motor can either work independently of the TDI engine or in tandem when accelerating. In pure electric mode the XL1 can travel up to 20 miles (35 km) before the diesel engine cuts in. Accelerating from rest to 60 mph can be achieved in 11.5 seconds; the electronically limited top speed is 99 mph.

In both its styling and packaging the XL1 draws on lessons learned from the 1-Litre car (2002) and the L1 concept (2009). The XL1 has evolved to feature staggered seating with the driver and passenger placed next to each other in a body structure made from advanced new materials providing immense strength yet weighing just 507 lbs (230 kg).

To make such weight savings possible, and yet viable for series production, Volkswagen developed and patented a new system for the manufacture of the Carbon Fiber Reinforced Polymer (CFRP) parts on the car called the Resin Transfer Moulding (RTM) process.

In total the XL1 weighs 1753 lbs. In addition to the body structure, the weight is accounted for by the drivetrain, the running gear, the interior including a pair of bucket seats and the electrical system. In total just 23.2 per cent of the car is made out of either steel or iron.

Further savings are made through the extensive use of lightweight materials including magnesium (wheels), ceramics (brake discs) and aluminum (dampers, steering system, brake calipers).

The styling of the XL1 is borne out of functional requirements - easy access to the interior is granted via a pair of elegant scissor doors that hinge on the A-pillar while the profile of the car has been honed in the wind tunnel, the result being a remarkable coefficient of drag figure of 0.186. The XL1's overall length and width are similar to those of a Volkswagen Polo yet its height is more akin to that of a Lamborghini Gallardo Spyder.

Although the XL1 is still very much a concept, its unveiling marks the next step towards the birth of a new class of Super Efficient Vehicles, while the advent of a process such as RTM is a significant milestone.