The Audi A4 has been built in four generations and is based on Volkswagen's B platform. The first generation Audi A4 succeeded the Audi 80. The automaker's internal numbering treats the Audi A4 as a continuation of the Audi 80 lineage, with the initial Audi A4 designated as the B5-series, followed by the B6, B7, and the current B8. The B8 Audi A4 is built on Audi's new MLB platform, which is currently exclusive to Audi and not shared by models outside the Audi brand, including any from VW.
The Audi A4 automobile layout consists of a longitudinally oriented engine at the front, with transaxle-type transmissions mounted at the rear of the engine. The cars are front-wheel drive, or on some models, "quattro" four-wheel drive.
The Audi A4 is available as a saloon/sedan and estate/wagon. The second (B6) and third generations (B7) of the Audi A4 also had a convertible version.