First produced in 1994, the latest rendition of the A4 is based on a variant of the Audi Modular Longitudinal Platform, which is the same platform used in the Audi A5 coupe.
Design
The new A4 besides receiving an increment in the wheelbase is also longer by 117mm than the 3rd generation model, and has a wider and much more aggressive stance. The Modular Longitudinal platform ensures that the new A4 has shorter front overhangs, which automatically translates into a longer wheelbase, but without the same increase in overall length. Although there has been an increase in the overall dimensions of the car, the curb weight has dipped some 10%.

Quite easily one of the most impressive and elegant looking sedans in Audi's line-up, the A4 has been endowed with modern contemporary design trends. The front is where the real beauty lies in the form of the gorgeous pearl LED daytime running lights, chrome tipped split radiator grille and a snazzy bumper with circular fog lamps. The stretched hood gels beautifully with the angular roof and short boot, and along with the finely sculpted flanks makes for a sedan that besides looking aggressive also looks paints a sporty portrait. The diesel A4 though looks a tad subdued and wears 7 spoke 16 inch alloys, while in the petrol avatar, the A4 features stunning 5 spoke 17 inch alloys with low profile tyres that compliment the overall design of the car. The A4 has a 480 litre boot and offers 20 litre of additional storage space than the BMW 3 Series.

Step inside and one is welcomed by a racy centre console, dash and a sporty 3 spoke steering wheel in case of the petrol version accompanied by brushed aluminium inserts. The instrument panel although not cluttered in the least bit is a tad complex with its wide array of buttons and knobs. Wood on the dash and centre console is reminiscent of that of the BMW 3 Series, and is pretty much a norm for any sedan that dares to call itself classy and elegant. The sporty steering wheel in the petrol comes with paddles to work the auto box. The quality of plastics that have been employed is of top-notch quality but some of the buttons are not as soft to touch as one would have liked it to be.

As a result of the increment in length and wheelbase, the new A4 is very spacious on the inside and can seat five adults with ease. Both the petrol and the diesel variants have ample leg room and head room, surpassing that of its bitter Teutonic rivals. For taller drivers though, knee room is a tad cramped as the centre console takes up a considerable amount of space. The new Audi A4 has highly supportive and contoured seats, and is comfort personified. The interior of the A4 to put it quite bluntly is of the highest quality and is by far the best in its class.
Comfort
The Audi A4 has a more than generous level of equipment for the comfort of its passengers. Large comfortable leather seats, 4-way electronically adjustable lumbar support for the driver and front passenger, electronically adjustable rear shades, automatic climate control, cruise control, rear parking sensors, 3-zone aircon and multi-function steering wheel makes the Audi A4 a true delight for both driver as well as passengers. And then there is the Multi-Media interface system which is said to be better and easier to use than the BMW iDrive system. For in-car entertainment, the A4 boasts of a 505watt Bang & Olufsen sound system which comprises of 14 high-performance loudspeakers.

The Audi A4 is fitted at the front with a five-link suspension and a self-tracking trapezoidal link rear suspension which is mated to larger shock absorbers from the A6. Ride quality is top-notch and incredibly refined as the all-aluminium suspension allows for a large amount of longitudinal conformity. Handling too is spot on and there is minimal body roll. Spirited cornering is absolutely on the cards as the A4 grips the road beautifully. There is a wee bit of under-steer though in the Quattro, but nothing that can't be overlooked. The Audi drive select system adjusts the suspension to meet the standard of the road as well as the mood of the driver. Comfort mode is the most favoured mode for city driving as the steering becomes light. In Dynamic mode, the suspension becomes stiffer for better handling, while in auto mode the car adjusts to the drivers driving style. What's most pleasing about the A4's ride quality is the fact that it is not at all stiff and incredibly smooth even when driving over rough terrains.
Engine, Transmission and Performance
The flagship A4 is the Quattro powertrain 3.2 FSI petrol, while the diesel 2.0 litre TDI has been offered to woo fans of diesel power to its shores. The direct fuel injection 3.2 litre V6 petrol which feature Audi's valve lift system generates 265bhp@6500rpm and a torque of 33.7kgm available from 3000rpm onwards, the redline being at 5000rpm. This highly refined engine has an extraordinarily smooth and linear flow of power thanks to the direct injection and new valve lift system. However, since torque comes into play from 3000rpm onwards only, the engine has to be initially worked up fairly for the juices to get flowing.

Taking only 8.46 seconds to race from 0-100 kph, the Quattro is fast and has a definitive punch; maximum speed is a staggering 250kph. FSI engines with direct injection are much more powerful than the indirect fuel injection versions and are known for their impressive fuel economy and cleaner emissions. The petrol Audi A4 has an overall mileage of 7.2kmpl.

The 1968cc in-line 4 cylinder turbodiesel A4 produces 145bhp@4200rpm and a torque of 32.6kgm available between 1750-2500rpm. The common-rail unit with pump injection technology is smooth and refined like the petrol unit but lacks its power and the grunt. Nevertheless, the 2.0 litre TDI as a result of the variable geometry turbo has very little drag and the rate of response and acceleration is quite impressive. The diesel A4 has a maximum speed of 210kph and takes 10.78 seconds to attain a speed of 100kph from stop. The diesel though beats the petrol version when it comes to fuel-efficiency, returning 8.6kmpl in the city and a very decent 17.6kmpl on the highway.

While the 3.2 Quattro is mated to a 6-speed DSG automatic gearshift, the diesel gets a Multitronic 8-speed CVT transmission that also has a sports mode. The DSG automatic is nothing short of brilliant, allowing brisk shifts. The DSG gearshift can be worked manually as well with paddlers being located behind the steering wheel.
Safety
The Audi A4 has a 5 star safety rating and comes with a host of the latest active and passive safety features. There is immense braking power in the A4 due to the presence of Electronic Stabilisation program (ESP) which mates the ABS with Electronic Break-pressure Distribution (EBD). The presence of 6 airbags is a comforting thought and protects the passengers from the side and front. In addition, there is a vehicle stability control system and traction control system which helps in maintaing a healthy body control. Safety is of supreme importance for a high-end sedan and the Audi A4 certainly is not lacking in this department. The Audi A4 is not exactly cheap but when it comes to quality, refinement and substance, it no doubt reigns supreme. It is Vorsprung Durch Technik in the truest sense of the word.  The 2.0 litre TDI sports a price tag of Rs. 29 Lakhs (ex showroom Delhi), while the more powerful 3.2 Quattro FSI comes for Rs. 36 Lakhs (ex showroom Delhi).