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 A8L W12), Audi has usually engineered its more expensive cars with a longitudinally 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.