Manual transmission, S tronic and tiptronic, front-wheel and quattro drive – there are various solutions for power transmission in the new A4 models. Tailored technology is available for each engine.
The manual transmission, which is standard equipment for all TFSI engines and for the four-cylinder TDI engine, is an all-new development. Much of its housing is made of magnesium. A spur-gear stage replaces the shaft to the front-axle differential used on the previous model, providing great advantages in terms of friction and space requirements. Open gearwheels, hollow shafts and a smaller clutch reduce the transmission’s weight further with the end result that the new unit is 16 kilograms (35.3 lb) lighter than the old one.
Audi’s new seven-speed S tronic is available for all engines except the top TDI and is standard equipment for the 3.0 TDI clean diesel with 160 kW (218 hp)*. The dual-clutch transmission, which replaces the continuously variable multitronic transmission, features excellent efficiency. The most important improvements are a further reduction in friction, the low weight, highly efficient oil lines and a centrifugal pendulum-type absorber on the dual-mass flywheel which allows very low idling speeds.
The two compact multi-disc clutches of the new seven-speed S tronic are arranged axially behind each other instead of – as with the predecessor – radially above each other, which reduces drag torque. They operate two separate sub-transmissions, which are constructed like manual transmissions. They are permanently active but only one of them is connected to the engine.
Gear shifts take place within a few hundredths of a second by means of clutch operations, and with virtually no interruption of traction. With the quattro transmissions, power is transmitted from the drive shaft through a spur-gear stage to the front-axle differential.
Smooth and fast: the eight-speed tiptronic
The eight-speed tiptronic is available only with the 3.0 TDI clean diesel with 200 kW (272 hp)*. The smooth, rapid and spontaneously shifting torque-converter transmission is another all-new development. Its high number of gears allows the engine to be operated close to its ideal load for more of the time. A new engine-speed-adaptive vibration absorber allows the powerful V6 diesel engine to run smoothly even at just 850 rpm. The design of the gear sets and shifting elements ensures low drag torque, which results in high efficiency.
Both automatic transmissions in the new A4 series are state of the art and feature a wide spread of gears: Their lower gears have sporty low ratios and high ratios for the upper gears to reduce engine speed and fuel consumption.
The S tronic and the tiptronic are integrated into the engine’s thermal management and designed for start-stop operation. The driver can select between modes D, S and E and can manually shift gears at any time with the selector lever or with the standard shift paddles on the steering wheel. All the driver’s inputs are transmitted to the transmission electrically (“by wire”), a quick tap on the selector lever triggers the shift command.
The new cruise control includes an impressive efficiency function: When the driver lifts his or her foot from the accelerator pedal in mode D or E, the transmission shifts to freewheeling whenever that would result in fuel savings. This coasting mode is possible between 55 and 160 km/h (34.2-99.4 mph). The function can anticipate even more effectively when a car has the optional systems predictive efficiency assist and Stop&Go adaptive cruise control including traffic-jam assist.
Front-wheel drive is standard equipment in the new Audi A4 family. With the gasoline engines, quattro permanent all-wheel drive is available for the 2.0 TFSI with 185 kW (245 hp)*. For the diesel engines it is available as of the 2.0 TDI with 140 kW (190 hp)* and is standard equipment for the most powerful 3.0 TDI with 200 kW (272 hp)*.
quattro permanent all-wheel drive
Audi’s quattro all-wheel drive is the ultimate in terms of dynamics, traction, safety and straight-line reliability. It is a purely mechanical system and therefore operates without any delay. In normal operation, its self-locking central differential, which is designed as a planetary gear train, transfers 60 percent of the engine’s torque to the rear axle and 40 percent to the front. Depending onthe situation, up to 70 percent of the torque can be transferred to the front and up to 85 percent to the rear. These high limits allow a clearly defined torque distribution and extremely precise interaction with the control systems.
The further developed wheel-selective torque control is a drivetrain “partner” and is now active on all road surfaces. During dynamic cornering, the software function slightly brakes the front wheel on the inner side of the curve (with front-wheel drive) or both inner wheels (with quattro drive) before wheelspin occurs. This also takes place when the drier is not pressing the accelerator. Due to the different forces, the car turns slightly into the curve; the roll-steer effect remains neutral for longer and the car’s handling is more precise, agile and stable.
The sport differential, optional for the top TDI as of 2016, optimizes handling. It actively splits torque between the rear wheels through two stages. During sportier driving, the system literally pushes the car into the curve, eliminating any tendency to understeer. This function, which is managed by a newly developed control unit – the electronic suspension program – is integrated into Audi drive select. The sport differential reacts faster than that of the previous model and is approximately one kilogram lighter.
*The fuel consumption and CO2 emission figures of all models named above and available on the German market can be found in the list on the last page of this basic information.