Audi has announced a new 2.0 litre TFSI engine at this year’s Vienna Motor Symposium. The new 1,984 cc engine will make its debut in the all-new B9 Audi A4 by the end of 2015.

Output is rated at 190 horsepower and 320 Nm of torque available from as low as 1,450-4,400 rpm. In the new A4, the engine is claimed to have an NEDC cycle fuel consumption of less than 5 litres per 100 km. Audi says the new 2.0 TFSI engine will be the most fuel efficient in its class. As a comparison, the 2.0 litre engine in the BMW 320i is rated at 6 litres per 100 km on the NEDC cycle.

The secret to the engine’s fuel efficiency is a new combustion method. Audi likens it to a further developed version of a Miller cycle. What they’ve done is reduce intake time – the engine uses a 140 degree crank angle rather than a 190 to 200 degree one. For higher loads, the Audi Valvelift System allows a longer load time at 170 degree crank angle.

Thanks to a higher boost pressure on the inlet side, the engine attains optimal cylinder charges despite the shorter intake time. The intake valve also closes earlier before the bottom dead centre is reached. This lowers the medium pressure, allowing a high, efficiency-boosting compression ratio.

An additional injection upstream from the intake valve yields an efficient mixture formation that is already complemented by the direct injection in the intake manifold and in the combustion chamber.

Other features include a controlled coolant flow to shorten engine warm-up time, an integrated exhaust manifold, and a low friction 0W20 engine oil. The engine itself is also light, weighing about 140 kg.

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GALLERY: Audi A4 B9 render/spyshots