Audi introduced a revised A4 in late 2004, with the internal designation of B7. 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.
Audi's internal platform nomenclature uses PL46 (passenger car longitudinal platform, size 4, generation 6) for both B6 and B7 chassis. The Typ 8E and Typ 8H internal designations are also carried over from the B6 A4 range, but now have an additional identifying suffix – 8EC for the saloon, 8ED for the Avant, and 8HE for the Cabriolet.
The engine lineup received many additions. The 2005 introduction of Fuel Stratified Injection (FSI) on the 2.0 TFSI and 3.2 V6 FSI petrol/gasoline engines, as well as other refinements, increased power output to 200 PS (147 kW; 197 bhp) and 255 PS (188 kW; 252 bhp), respectively. These engines both use a four-valve per cylinder configuration. The prior 5-valve design was incompatible with the FSI direct injection system (due to the siting of the fuel injector, now discharging directly into the combustion chamber). The 2.0 Turbocharged Direct Injection (TDI) diesel engine now combined Pumpe Düse (Unit Injector) (PD) technology with 16 valves, while the larger 2.5 TDI V6 diesel was superseded by a 3.0 V6 TDI, offering a 204 PS (150 kW; 201 bhp) model during the year 2005 which was upgraded to a 233 PS (171 kW; 230 bhp) model in 2006. A 2.7 V6 TDI was added later.
Torsen T-2 based quattro permanent four-wheel drive remained as an option on most A4 models. Audi retired its 5-speed manual transmissions in favour of a new Getrag 6-speed. As before, multitronic continuously variable transmission (CVT), now with selectable 'seven-speeds', was an option on front-wheel drive models, whilst a conventional ZF 6HP 6-speed tiptronic automatic transmission was an option on the quattro four-wheel drive models.
In addition to the Audi S4, which carried over the powertrain from the B6 S4 – Audi reintroduced the quattro GmbH developed Audi RS4 (RS for RennSport) to the lineup, for the first time on the saloon/sedan and Cabriolet body, and with a naturally aspirated, but high-revving 4.2-litre V8 FSI engine. Another notable[according to whom?] inclusion on the RS4 is the latest generation Torsen T-3 quattro 4wd system, which uses a 'default' asymmetric 40:60 front-rear dynamic torque distribution bias. This new asymmetric centre differential was initially only available on the RS4, but was added a year later on the S4. The remainder of the B7 A4 range still used the T-2 50:50 default dynamic split centre diff.
Audi A4 DTM Edition
A variant, developed by quattro GmbH, was first introduced in May 2005, named "Audi A4 DTM Edition". It was inspired from Audi's race cars of the 2004 Deutsche Tourenwagen Masters, and was reintroduced in 2006 as a regular option. 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. It was available with front-wheel drive, or quattro four-wheel drive.
The B7 Cabriolet model arrived later than the other two body variants, with sales beginning in February 2006. New on the Cabriolet was an entry-level 2.0 TDI version, which was not offered with the multitronic CVT gearbox.
In 2007 Audi introduced a version of the B7 named the 'Special Edition', which built on the S-Line specification and also included the black optics pack, the RS4 style 8J X 18 '7-arm double spoke' design alloy wheels, Two-tone Graphite/Black Volterra leather, 3-spoke sports leather/Alcantara multi-function steering wheel with gear knob and hand brake handle in Alcantara with silver stitching, ventilated cross-drilled front disc-brakes, black tailpipes and black roof rails (Avant model only). It also had a power increase of 20 PS, giving an output of 220 PS on the 2.0T model.
According to 2007 Swedish vehicle inspection data, the Audi A4 Avant with diesel engine is the most reliable vehicle available on the market, with vehicle inspection rejection rate of 0.0% in three-year-old category.
