[2] The first generation Audi A4 (known internally as the Typ 8D) debuted in October 1994,[5][6] with production starting November 1994 and European sales commencing in January 1995 for the 1995 model year.

Moreover, a quattro GmbH special edition of the B5 1.8T was later available in Germany and Europe, for which the engine's power output was raised to 180 PS (132 kW; 178 bhp) and 235 N⋅m (173 lb⋅ft).

The transmission is a conventional automatic gearbox with a torque converter offering the driver a fully-automatic operation or manual selection of the gear ratios.

Moreover, a significant facelift was introduced for the 1998 B5 model year at the 1997 Frankfurt Motor Show, with sales beginning in Europe in early 1998.

The previous KKK K03 turbocharger, although fundamentally unchanged, received revisions on the turbine side to prevent cracking due to heat.

The car's new styling was developed under Peter Schreyer between 1996 and 1998, inspired by the Bauhaus design language of the C5 (second-generation) Audi A6 introduced in 1997.

The 1.9 Turbocharged Direct Injection (TDI) engine was upgraded to 130 PS (96 kW; 128 bhp), with Pumpe Düse (Unit Injector) (PD) technology, and was now available with quattro permanent four-wheel drive, while the 2.5 V6 TDI high-end model was introduced with 180 PS (132 kW; 178 bhp) and standard quattro.

The rear light assemblies now formed part of the top line, these styling cues were eventually borrowed by other European as well as Asian manufacturers.

The Insurance Institute for Highway Safety (IIHS) awarded both the B6 & B7 a "Good" rating in the frontal crash test; the B7 was not retested since the front portion is structurally the same.

Although given a new platform designation, the B7 was essentially a heavily facelifted and revised version of the B6, with revised steering settings, suspension geometry,[specify] new internal combustion engine ranges, navigation systems and chassis electronics (including a new advanced Bosch ESP 8.0 Electronic Stability Programme (ESP) system).

The front grille assembly changed to a tall trapezoidal shape in the same manner as the C6 (third-generation) Audi A6; however, the dashboard and interior were virtually unchanged from the B6 aside from minor detailing.

Another inclusion on the RS4 was the latest generation Torsen T-3 Quattro 4WD system, which uses a 'default' asymmetric 40:60 front-rear dynamic torque distribution bias.

The 2.0T FSI engine received revised software mapping to the ECU, which increased the output to 220 PS (162 kW; 217 bhp) and 300 N⋅m (221 lb⋅ft) of torque.

[26][failed verification] When the successor B8 A4 range was introduced, the B7 series A4 was restyled and rebadged as the SEAT Exeo in 2008 with changes to the front and rear plus interior trim from the A4 Cabriolet.

Audi released the first official pictures of the B8 series A4 in August 2007 and unveiled the car to the public at the September 2007 Frankfurt Motor Show.

[33] This effectively redistributes the centre of gravity slightly rearwards, improving handling by better balancing vehicle mass between the front and rear axles.

[34] The transfer shaft, however, has the effect of creating a large "bulge" on one side of the transmission tunnel, which on right-hand drive versions forces the pedals to be badly offset, which has attracted criticism from the British motoring press in particular.

Reception has been mixed, with praise for the Audi A4's increased size, giving it best-in-class rear legroom and trunk space in the compact executive car segment.

Audi released the first official pictures of the B8 series A4 in August 2007 and unveiled the car to the public at the September 2007 Frankfurt Motor Show.

The quattro permanent four-wheel drive system uses the latest Torsen T-3 centre differential, with a default 40:60 front to rear asymmetric torque distribution ratio (used first on the B7 RS4) as standard.

Volkswagen settled a class-action lawsuit in 2013 involving the failures of the CVT transmission in its Audi A4 and A6 automobiles for model years 2002–2006.

It features redesigned LED headlamps and taillights, front air dam with fog lamps, and closely set twin exhausts.

Interior changes include Bluetooth connectivity for audio streaming (nav equipped models only) and a redesigned ignition key.

A new "Drive Select System" allows drivers to choose comfort, dynamic, individual, or efficiency modes for fuel-efficiency.

The B9 is slightly larger than the outgoing B8, but Audi claims the new A4 is around 120 kg (265 lb) lighter than its predecessor due to the use of its new lightweight aluminum-hybrid construction.

The B9 also comes with a number of A4 firsts such as virtual cockpit, Apple CarPlay and Android Auto, full-color head-up display, and Audi pre-sense.

The S Line package uses skirts, bumpers, seats and wheels from the Audi S4, and adds an aluminum inlay to the interior consoles.

In addition to redesigned headlights and taillights, almost every body panel on the A4 was altered, with only the hood, trunk and roof remaining untouched.

Notably, the character line that ran the length of the A4 was removed, with creases added to the front and rear fenders in its place.

In addition to the above packages, Audi also manufactures aftermarket accessories for the A4, including decals, spoilers, mirror caps and tail pipes.