and the narrow angle of each set of cylinders allows just two overhead camshafts to drive each pair of banks, so just four are needed in total. The advantage of the W12 engine is its compact packaging, allowing Audi to build a 12-cylinder sedan with all-wheel drive, whereas a conventional V12 engine could have only a rear-wheel drive configuration as it would have no space in the engine bay for a differential and other components required to power the front wheels. In fact, the 6.0 L W12 in the Audi A8L W12 is smaller in overall dimensions than the 4.2 L V8 that powers the Audi A8 4.2 variants. The 2011 Audi A8 debuted a revised 6.3-litre version of the W12 (WR12) engine with . Fuel Stratified Injection New models of the A3, A4, A6 and A8 have been introduced, with the ageing 1.8-litre engine now having been replaced by new Fuel Stratified Injection (FSI) engines. Nearly every petroleum burning model in the range now incorporates this fuel-saving technology. Direct-Shift Gearbox In 2003, Volkswagen introduced the Direct-Shift Gearbox (DSG), a type of dual-clutch transmission. It is a type of automatic transmission, drivable like a conventional torque converter automatic transmission. Based on the gearbox found in the Group B S1, the system includes dual electro-hydraulically controlled clutches instead of a torque converter. This is implemented in some VW Golfs, Audi A3, Audi A4 and TT models where DSG is called S-Tronic. LED daytime running lights Beginning in 2005, Audi has implemented white LED technology as daytime running lights (DRL) in their products. The distinctive shape of the DRLs has become a trademark of sorts. LEDs were first introduced on the Audi A8 W12, the world's first production car to have LED DRLs, and have since spread throughout the entire model range. The LEDs are present on some Audi billboards. Since 2010, Audi has also offered the LED technology in low- and high-beam headlights. Multi Media Interface Starting with the 2003 Audi A8, Audi has used a centralised control interface for its on-board infotainment systems, called Multi Media Interface (MMI). It is essentially a rotating control knob and 'segment' buttons – designed to control all in-car entertainment devices (radio, CD changer, iPod, TV tuner), satellite navigation, heating and ventilation, and other car controls with a screen. The availability of MMI has gradually filtered down the Audi lineup, and following its introduction on