B5 A4 (8D) (1994–2001)Edit
The first-generation Audi A4 (known internally as the Typ 8D) was debuted by Audi in 1994 on the Volkswagen B5 platform, which it shared with the fourth generation Volkswagen Passat. It had a longitudinal engine and standard front-wheel drive, although many of the A4 owners selected the optional quattro four-wheel drive system. The A4 was initially introduced as a four-door saloon/sedan; the Avant (estate/wagon) arrived a year later.
A wide range of engines were available to European customers, between 1.6 and 2.8 litres, and a 1.9 L Diesel available with VW's new "Pumpe Düse" (PD, or unit injector) technology, capable of achieving a then high power value of 110 PS (81 kW), although Audi's 2.8 L V6, carried over from the old 80/90 was the only engine option in North America until 1997.
The Audi A4 was the first model in the Volkswagen Group to feature the new 1.8 L 20V motor with five valves per cylinder, based on the unit Audi Sport had developed for their Supertouring race car. A turbocharged version produced 150 PS (110 kW) and 210 Nm (155 ft·lbf.) of torque. This technology was added to the V6 family in 1996, starting with the 2.8 L V6 30V, which now produced 193 PS (142 kW).
Audi also debuted their new Tiptronic transmission on the B5 platform, based on the unit Porsche developed for their 964-generation 911. The transmission is a conventional automatic gearbox with a torque converter, but it offers the driver a choice of driving the car as either a fully automatic operation or with a manual override of the gear ratios.
The B5 A4 was arguably a watershed model for Audi. The massive improvement in quality and engineering with the B5 A4 made buyers realise that there was a luxury German marque other than BMW and Mercedes-Benz. Combined with the well-received TT concept (later a production car), Audi emerged as one of the leaders in the luxury car market.
The Audi A4 (B5) passed the Euro NCAP crash tests, the A4 3 stars from front and side impact but but the last star is flagged to indicate that the driver has high risk of chest injury in the side impact, it was awarded the following car safety ratings: 
B5 facelift (1998–2001)Edit
Audi refreshed the model in the 1997 Frankfurt Motor Show, with sales beginning in Europe in early 1998. Besides the introduction of a 2.8 L 30-valve V6 (replacing the 2.8 L 12-valve), the most important additions to the range were the 2.5 L V6 TDI (diesel) engine with 150 PS (110 kW) and standard quattro, and a six-speed gearbox, as well the new high-performance S4, now part of the A4 lineup (the previous S4 had been an Audi 100). New taillights, headlights, door handles, and other minor exterior/interior changes rounded out the cosmetic updates.
In mid 1998, the 1.8T engine available outside Europe had its power output raised to 170 PS (125 kW). This was accomplished by upgrading the previous KKK KO3 turbocharger with a KO3s(sport) unit. The 12-valve V6 was replaced by the 30-valve unit that had been available in Europe for two years. In 1999, Audi debuted an even higher performance RennSport model, the RS4, like its predecessor RS2 available only in the Avant body.
A4-derived hybrid versionEdit
B6 A4 (8E) (2001–2005)Edit
An all-new A4, internally designated Typ 8E, debuted in late 2000, now riding on the all new Volkswagen B6 (PL46) platform. The car's new styling was inspired on the C5 (second-generation) Audi A6. The 1.6 L base model remained unchanged, but most other petrol/gasoline engines received either displacement increases, or power upgrades. The 1.8 L 20-valve Turbo was now available in two additional versions, with 150 or 180 PS (110 or 132 kW), this one with a standard six-speed gearbox, while the naturally aspirated 1.8 L straight-4 and 2.8 L V6 were replaced by 2.0 L and all-aluminium 3.0 L units, still with five valves per cylinder, the most powerful of which was capable of 220 PS (162 kW) and 300 Nm (221 ft·lbf) of torque. The 1.9 TDI engine was upgraded to 130 PS 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) and standard quattro. The Avant arrived in mid 2001. This generation of quattro consists of default of 50:50 front to rear torque distribution, infinitely variable up to 25:75 or 75:25.
For 2002, Audi upgraded power in the 1.8 Turbo engines to 163 and 190 PS (120 and 140 kW respectively) - 190 designated by a red T, with both available with quattro, and in the 2.5 TDI intermediate version to 163 PS. A 2.0 engine with Fuel Stratified Injection was also available. A year later, Audi reintroduced the S4, now powered by a 344 PS (253 kW) 4.2 L V8 engine, as well as an A4 Cabriolet convertible variant (Typ 8H), finally replacing the 80-based Audi Cabriolet that had been discontinued in 1998. It included an electro-hydraulic operated hood, which lowered in under 30 seconds and incorporated some styling changes which eventually found their way to the saloon version (such as body-colored lower bumper and sill panels).
Audi also introduced a continuously variable transmission developed by LuK, named multitronic, which replaced the Tiptronic on front-wheel drive models. The transmission won considerable praise from the automotive press, and is generally regarded as being the best of its type in the world, due to its light weight and promptness in response, but its use was limited to models with a maximum of 310 Nm (229 ft·lbf).
Borrowing from the Audi A6, the boot was redesigned to remove the extension of the top edge with a smoother fold line, and the taillight assembly now forms part of the top line.
An "Ultra sport package" named Ultra Sport was introduced in the North American market shortly before the B6 was replaced by the B7. It included aluminium interior trim and door sills, "S line" steering wheel, front and rear spoilers, side valence and Template:Convert RS4 replica wheels.
|2.0 20V||4||Template:Auto PS|
|1.8T 20V||4||Template:Auto PS / Template:Auto PS|
|1.8T S-Line||4||Template:Auto PS / Template:Auto PS|
|2.4 30V||V6||Template:Auto PS|
|3.0 30V||V6||Template:Auto PS|
|S4 4.2||V8||Template:Auto PS|
|1.9 TDI||4||Template:Auto PS / Template:Auto PS|
|2.5 TDI||V6||Template:Auto PS / Template:Auto PS|
B7 A4 (8E) (2005–present)Edit
Audi introduced a heavily revised A4 in late 2004, with the internal designation of B7. However, this new range A4 still utilised the existing Volkswagen B6 (PL46) platform, a chassis derived from the outgoing B6, but enjoyed heavily revised steering settings, suspension geometry, new engine ranges, navigation systems and chassis electronics (a new advanced Bosch 8.0 ESP system). Audi's internal platform nomenclature uses PL46 (longitudinal passenger car platform, size 4, generation 6) for both B6 and B7 chassis. The Typ 8E and 8H internal designations are also unchanged from the B6 A4.
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 and 255 PS (147 and 188 kW), respectively. These engines both implement a four-valve per cylinder design. The prior 5-valve design was incompatible with the FSI direct injection system. The 2.0 TDI diesel engine now combines Pumpe Düse (PD) technology with 16 valves for the first time, while the larger 2.5 TDI was increased to 3.0 L, offering 204 PS (150 kW). quattro permanent four-wheel drive remained available on most A4 models. Audi retired its 5-speed manual transmissions in favour of a 6-speed. As before, multitronic transmission is available on front-wheel drive models, while a 6-speed Tiptronic transmission is available on quattro four-wheel drive models.
In addition to the higher-performance S4, which carried over the powertrain of the B6 S4, Audi has reintroduced the ultra-high performance RS4 (RS for RennSport) to the lineup, for the first time on the saloon/sedan and Cabriolet body and with a normally aspirated 4.2 V8 FSI engine. Another notable inclusion is the 3rd-generation Torsen T-3 quattro system, which uses a 'default' asymmetric 40:60 front-rear torque distribution (this new asymmetric centre differential was only available initially on the RS4, and later, on the S4. The remainder of the A4 range still utilised the 50:50 split diff). A limited edition variant first introduced in late 2005, named "DTM Edition", was reintroduced in 2006 as a regular option, the 2.0T FSI engine now engineered to 220 PS (162 kW) with standard quattro. The front grill assembly has changed to be a tall trapezoidal shape in the same manner as the C6 (third-generation) Audi A6.
The B7 Cabriolet model arrived later than the other two body variants, with sales beginning in February 2006. Brand new on the Cabriolet was an entry-level 2.0 TDI version, but to date this is not being offered with the Multitronic gearbox.
The Audi A4 offers many safety features, including side airbags, anti-lock brakes (ABS), Electronic Stabilization Programme, and its optional quattro four-wheel drive. It also received the IIHS "Top Safety Pick For 2007" 
B8 A4 (8K) (2008–present)Edit
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 Auto Show. Saloon/sedan and Avant models are offered. The Avant was unveiled to the public at the March 2008 Geneva Auto Show.
The B8 A4 substantially shares the same underpinnings as the Audi A5 coupé. Compared to prior A4 chassis, the front axle is moved forward with respect to the engine. This effectively moves the engine mass slightly rearwards, improving the weight balance and handling by more evenly distributing the weight on all four tyres. The estimated static front:rear weight ratio of the B8 is approximately 55:45, depending on body style and engine selection.
The B8 A4 has increased in length by approximately 12 cm over the prior B7, which has allowed for increased rear seating legroom. Although the overall dimension have increased, the curb weight has dropped some 10%. The boot (trunk) has also increased to 480 litres (17 cu ft) for the saloon (sedan) version. A4 Avant will have a maximum capacity of 1,430 litres with the rear seats folded down.
Significant new features have been developed for the B8. As standard the A4 includes:
- LED Daylight running lights (only on the S-line trim and above);
- Light and rain sensors;
- MMI system (Multi Media Interface) (multi-mode interface of driver information and entertainment systems);
- Electronic park brake
- Speed sensitive steering (servotronic)
- Steering wheel multifunction;
- Lane departure and blind spot warning systems;
- Adaptive cruise control;
- Advanced Key (keyless entry and start);
- Sunroof, with electronic adjustable glass tints;
- Bang and Olufsen Sound system (505W);
- Advanced parking system Front and rear plus camera;
- Navigation system with full MMI with 7 inch screen;
- Adaptive headlights (Cornering technology);
- Auto dimming interior mirror;
- Comfort pack. Blue tooth, 3 zone climate control, electric seats.
- 1.8 litre (1798 cc) 16-valve I4 (petrol/gasoline); 160 PS (118 kW); top speed: Template:Auto km/h; 0-100 km/h; 8.6 s; Template:Convert
- 3.2 litre (3123 cc) 24-valve V6 (petrol/gasoline); 265 PS (195 kW); top speed: Template:Auto km/h; 0-100 km/h; 6.2 s; Template:Convert
- 2.0 litre (1968 cc) 16-valve TDI I4 (diesel); 143 PS (105 kW); top speed: Template:Auto km/h; 0-100 km/h; 9.4 s; Template:Convert
- 2.7 litre (2698 cc) 24-valve TDI V6 (diesel); 190 PS (140 kW); top speed: Template:Auto km/h; 0-100 km/h; 7.7 s; Template:Convert
- 3.0 litre (2967 cc) 24-valve TDI V6 (diesel); 239 PS (176 kW); top speed: Template:Auto km/h; 0-100 km/h; 6.1 s; Template:Convert
3.2 L V6 petrol (gasoline) and 3.0 L V6 diesel engines come with the quattro permanent four-wheel drive system, now with a default 40:60 front to rear asymmetric torque distribution ratio (used on the B7 RS4) as standard. Previous A4 quattro models split torque with a default front:rear 50:50. The additional torque applied to the rear wheels helps mimic the driving dynamics of rear wheel drive cars.
- Adult occupant = Template:Rating-5
- Child occupant = Template:Rating-5
- Pedestrian = Template:Rating-4
- Official Audi A4 Website (In German)
- Official Audi USA A4 Website
- Official Audi A4 UK Microsite
- Official Audi Canada A4 Website
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