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A very sporty 3.0 TDI is now being offered for the Audi A4 sedan in Australia.

This engine is the first and most-powerful 6-cylinder diesel engine in the B-segment.

Equipped with common rail technology and piezo injectors, the 3.0 V6 TDI engine delivers 171 kW (233 bhp), making it the most powerful diesel in its class.

The A4 3.0 TDI quattro reaches the 100 km/h mark in just 7.5 seconds and accelerates on up to a top speed of 245 km/h. Its fuel consumption, on the other hand, remains low, at just 8.4 litres per 100 km.

Further fortes are the engine's highly efficient noise management and fulfilment of the strict EU4 emissions standard.

Featuring turbocharger technology and map-controlled, cooled exhaust-gas recirculation, this V6 four-valve power unit is the first six-cylinder TDI in Audi's new family of V-configuration engines. Both the camshafts and the oil pump, incidentally, are driven by chains.

Like all engines in Audi's new V-generation, the V6 TDI has extremely compact dimensions, engine length, for example, measuring a mere 444 millimetres. This is also an important step in view of achieving an overall engine weight of just 219 kilos, making the 3.0 TDI one of the lightest V6 diesels in the world. This benefits not only the car's power-to-weight ratio, but also the weight distribution – two factors crucial to the superior driving dynamics of the new A4 3.0 TDI quattro.

Common rail technology with piezo inline injectors

Mixture preparation is by means of a latest-generation common rail system. It features a high-pressure pump and one rail per cylinder bank. This increases maximum injection pressure to 1,600 bar, 250 bar more than with previous common rail systems.

This high injection pressure results in even finer atomisation of the fuel and therefore in better mixture preparation and more efficient combustion.

The piezo injectors are undoubtedly the most important innovation of the new common rail system. The injection process makes use of the piezo effect: a voltage is applied to ceramic which changes its crystal structures. The result is a minimal geometric change which – supported by a hydraulic element – mechanically triggers the opening of the injector needle.

The piezo injectors offer multiple advantages compared with conventional solenoid valves. The moving mass at the injector needle is for instance reduced by no less than 75 percent, from 16 to 4 grams in each case. This enables considerably smaller and more precisely metered injection quantities. At the same time, piezo technology allows a higher injector needle speed.

The number of injection processes per combustion cycle can thus be varied almost at will. Audi’s TDI development engineers opted for up to five injection processes for the 3.0 V6: in addition to the main injection process, double pilot injection takes place at the lower end of the speed range and single pilot injection in the medium speed range.

This strategy produces both lower emissions and a smoother combustion process, the benefits of which are most immediately apparent in the engine's acoustic behaviour. The 3.0 TDI engine is not only much quieter and smoother running than its predecessor, it now unquestionably serves as the benchmark in its class.

Turbocharger with two intercoolers

For optimum charging of the combustion chamber in all operating conditions, the six-cylinder 3.0 TDI has a turbocharger accommodated inside the engine's "vee" to make optimum use of the available space. And to enhance efficiency to the highest level, the temperature of the intake air is reduced by two intercoolers running in parallel, any loss of pressure being kept to a minimum.

The exhaust gas is purified by a close-coupled primary catalytic converter – located close to the turbocharger – and the main converter under the floor. This enables the A4 3.0 TDI, as the first executive diesel of its kind, to clearly outperform the EU4 emission limits.

One feature of the new engine that is undoubtedly as welcome as its efficiency at reducing emissions is its impressive fuel economy. Its average consumption over 100 kilometres is just 8.4 litres of diesel. In practice this obviously means a very significant cruising range, the new A4 3.0 TDI quattro being able to cover almost 800 kilometres on one tank of fuel.

The Audi A4 3.0 TDI comes as standard with quattro permanent four-wheel drive and a 6-speed automatic transmission with tiptronic function and sport program.