In February 2012, Volkswagen confirmed that it would build a limited series of its long-awaited 1-litre car, likely to be named the XL1. Our spy photographers spotted the new model undergoing testing in Europe. The XL1 is the third iteration of the VW’s one-litre car, first shown in concept guise at the 2011 Qatar auto show. The previous concept cars were shown in 2002 and 2009 (then called the L1).RADICAL VWOur spy shots show, with a few modifications such as conventional rear-view mirrors, what the XL1 will look like when it finally heads into production. Like the L1, the XL1 uses an 800cc, two-cylinder turbo-diesel capable of 35kW and 121Nm as well as a 21kW/100Nm electric motor. The engine transmits power the rear wheels through a seven-speed DSG transmission. Fully charged, the XL1 can travel up to 35km on electric power and VW claims it can reach a top speed of 158km/h.According to Volkswagen, the XL1 can achieve a combined fuel consumption better that 100km/litre and has a CO2 emissions rating of 24g/km. The concept-car XL1 has a kerb weight of 795kg, with 23.2% of the car (184kg) made of either steel or iron, while the drivetrain weighs 227kg. AUDI R8 INSPIRED?The XL1's length and width are similar to the Volkswagen Polo at 3.9m and 1.6m respectively. The new model is much lower with a height of only 1.1m and has a coupe-like roofline, reducing interior space. The model spotted in our spy shots looks quite radical compared to anything in VW’s model line-up, though we can definitely see Audi R8 traits at the side and a Golf inspired front end.The design incorporates gullwing doors, with the interior seating similar to a Smart ForTwo. The XL1 is set make its debut early in 2013.