The XL1 is the third iteration of the Volkswagen 1-litre car, unveiled at the 2011 Qatar Motor Show. The diesel plug-in hybrid prototype is branded as a "Super Efficient Vehicle" (SEV).
According to Volkswagen, the XL1 can achieve a combined fuel consumption of 0.9 litres per 100 kilometres (310 mpg-imp; 260 mpg-US) and CO2 emissions of 24 g/km. Like the L1, the XL1 uses a two-cylinder turbo-diesel. Displacing 800 cm3 (49 cu in), it is rated at 35 kW (47 hp) and 121 N·m (89 lb·ft) of torque and transmits power to the rear wheels through a seven-speed DSG transmission. The electric motor pitches in with 20 kW (27 hp) and 100 N·m (74 lb·ft) of torque, and can work in parallel with the diesel or drive the car independent of it. Fully charged, the XL1 can travel up to 35 km (22 mi) on electric power.
The XL1 has a curb weight of 795 kg (1,753 lb), and a drag coefficient of Cd=0.186 (a similar drag coefficient to the General Motors EV1 electric car). Frontal area is 1.5 m2 giving a drag area of CdA=0.28 m2. Just 23.2% of the car (184 kg (406 lb)) is made out of either steel or iron; the drivetrain weighs 227 kg (500 lb). The XL1's length and width are similar to the Volkswagen Polo, with a length of 3,970 mm (156.3 in) and width of 1,682 mm (66.2 in). However, the car is much lower with a height of only 1,184 mm (46.6 in), and has a coupe-like roofline, reducing interior volume. The design incorporates butterfly doors, with the interior seating layout using a staggered side-by-side arrangement similar to a Smart Fortwo, rather than the previous versions' tandem seating.
Performance credentials include a governed top speed of 158 km/h (98.2 mph), with acceleration to 100 km/h (62.1 mph) in 11.9 seconds.
In February 2012, Volkswagen confirmed that it would build a limited series of XL1s starting in 2013. The production version of the plug-in diesel-electric hybrid was unveiled at the 2013 Geneva Motor Show.
In February 2013, Volkswagen announced that it expected the XL1 to achieve a fuel economy of 0.9 l/100 km (260 mpg-US; 310 mpg-imp) and emissions of 21 g/km of CO2. The test cycle allows for a re-charge of the battery every 75 km (47 mi) which results in a high mpg value. Using diesel alone the car is capable of up to 2.0 l/100 km (120 mpg-US; 140 mpg-imp). As with the 2011 concept XL1, it is powered by an 800 cm3 two-cylinder diesel engine with 35 kW (48 PS; 47 bhp) and a 20 kW (27 PS; 27 bhp) electric motor, delivering power to the rear wheels through a seven-speed dual-clutch gearbox. The drag coefficient has increased slightly from 0.186 to 0.189. The production version is expected to deliver an all-electric range of 50 km (31 mi).