Editing Audi (section)

===Drivetrains===

====Layout====
For most of its lineup (excluding the A3, A1, and TT models), Audi has not adopted the transverse engine layout which is typically found in economy cars (such as Peugeot and Citroën), since that would limit the type and power of engines that can be installed. To be able to mount powerful engines (such as a V8 engine in the [[Audi S4]] and [[Audi RS4]], as well as the [[W12 engine]] in the [[Audi A8|Audi A8L W12]]), Audi has usually engineered its more expensive cars with a [[Longitudinal engine|longitudinally]] [[Front-engine, front-wheel-drive layout|front-mounted engine]], in an "overhung" position, over the front wheels in front of the axle line—this layout dates back to the DKW and Auto Union saloons from the 1950s. But while this allows for the easy adoption of all-wheel drive, it goes against the ideal 50:50 weight distribution.

In all its post [[Volkswagen]] era models, Audi has firmly refused to adopt the traditional [[rear-wheel drive]] layout favored by its two archrivals [[Mercedes-Benz]] and [[BMW]], favoring either [[front-wheel drive]] or [[four-wheel drive|all-wheel drive]]. The majority of Audi's lineup in the United States features all-wheel drive standard on most of its expensive vehicles (only the entry-level trims of the A4 and A6 are available with front-wheel drive), in contrast to [[Mercedes-Benz]] and [[BMW]] whose lineup treats all-wheel drive as an option. BMW did not offer all-wheel drive on its V8-powered cars (as opposed to crossover SUVs) until the 2010 BMW 7 Series and 2011 BMW 5 Series, while the Audi A8 has had all-wheel drive available/standard since the 1990s. Regarding high-performance variants, [[Audi S and RS models]] have always had all-wheel drive, unlike their direct rivals from [[BMW M]] and [[Mercedes-AMG]] whose cars are rear-wheel drive only (although their performance crossover SUVs are all-wheel drive).

Audi has recently applied the ''quattro'' badge to models such as the A3 and TT which do not use the [[Torsen]]-based system as in prior years with a mechanical center differential, but with the [[Haldex Traction]] electro-mechanical clutch AWD system.

====Engines====
{{Further|List of Audi vehicles#Production model engines}}
[[File:Volkswagen W12.jpg|thumb|upright|[[Volkswagen Group]] W12 engine from the [[Volkswagen Phaeton|Volkswagen Phaeton W12]]]]

Prior to the introduction of the Audi 80 and Audi 50 in 1972 and 1974, respectively, Audi had led the development of the ''EA111'' and ''EA827'' [[Straight-four engine|inline-four]] engine families. These new power units underpinned the water-cooled revival of parent company Volkswagen (in the Polo, Golf, Passat and Scirocco), whilst the many derivatives and descendants of these two basic engine designs have appeared in every generation of VW Group vehicles right up to the present day.

In the 1980s, Audi, along with Volvo, was the champion of the [[Straight-five engine|inline-five]] cylinder, [[Engine displacement|2.1/2.2 L]] engine as a longer-lasting alternative to more traditional six-cylinder engines. This engine was used not only in production cars but also in their race cars. The 2.1&nbsp;L inline five-cylinder engine was used as a base for the [[Rallying|rally cars]] in the 1980s, providing well over {{convert|400|hp|kW|abbr=off}} after modification. Before 1990, there were engines produced with a displacement between 2.0&nbsp;L and 2.3&nbsp;L. This range of engine capacity allowed for both fuel economy and power.

For the ultra-luxury version of its [[Audi A8]] fullsize luxury flagship sedan, the Audi A8L W12, Audi uses the [[Volkswagen Group]] [[list of Volkswagen Group petrol engines#W12|W12 engine]] instead of the conventional [[V12 engine]] favored by rivals Mercedes-Benz and BMW. The W12 engine configuration (also known as a "WR12") is created by forming two imaginary narrow-angle 15° [[VR6 engine]]s at an angle of 72°, and the narrow angle of each set of cylinders allows just two [[overhead camshaft]]s 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&nbsp;L W12 in the Audi A8L W12 is smaller in overall dimensions than the 4.2&nbsp;L V8 that powers the Audi A8 4.2 variants.<ref>{{cite web |url=http://www.newcartestdrive.com/review-intro.cfm?Vehicle=2005_Audi_A8&ReviewID=2934 |title=2005 Audi A8 Review and Photos |website=New Car Test Drive |access-date=18 November 2011 |archive-url=https://web.archive.org/web/20131030011923/http://www.newcartestdrive.com/review-intro.cfm?Vehicle=2005_Audi_A8&ReviewID=2934 |archive-date=30 October 2013 }}</ref> The 2011 Audi A8 debuted a revised 6.3-litre version of the W12 (WR12) engine with {{convert|500|PS|kW hp|abbr=on}}.

====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 [[Gasoline direct injection|Fuel Stratified Injection]] (FSI) engines. Nearly every petroleum burning model in the range now incorporates this fuel-saving technology.

[[File:2007 Audi R8 Engine.JPG|thumb|V8 FSI engine]]

====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 [[clutch]]es instead of a [[torque converter]]. This is implemented in some [[Volkswagen Golf|VW Golfs]], [[Audi A3]], [[Audi A4]] and [[Audi TT|TT]] models where DSG is called S-Tronic.