Volkswagen’s XL1, presented in 2013, was the world’s most economical production car featuring a diesel plug-in hybrid powertrain, with fuel consumption of only 0.9 l/100 km. The powertrain consisted of a two-cylinder TDI engine (35 kW / 48 PS) and an electric motor (20 kW / 27 PS), a seven-speed dual-clutch gearbox (DSG) and a lithium-ion battery. The two-seater could be driven in full-electric mode with zero local emissions for a distance of up to 50 kilometers. The XL1 followed the design principles of a sports car: light weight (795 kg), perfect aerodynamics (Cw 0.189) and low centre of gravity (1,153 mm above ground). To achieve such economy, it was produced with lightweight materials, a streamlined body and an engine and transmission designed and tuned for economy. The concept car was modified first in 2009 as the L1 and again in 2011 as the XL1.