The Efficiency Principle

Smaller engine capacity, fewer cylinders, lower fuel consumption but the same or even better performance: Audi is adopting the principle of downsizing for its petrol engines. This combines the fuel efficiency of small engines with the power of larger ones. As a result, Audi also offers premium-quality vehicles for environmentally conscious drivers – without compromising driving pleasure.
A4 Avant (photo)

For a fraction of a second the intake and exhaust valves in the cylinder are both open, allowing fresh air to flood into the combustion chamber. It propels the exhaust gas swiftly towards the exhaust manifold, helping the turbocharger to press fresh oxygen into the cylinder. During this process the injection valve stands still, before pumping the fuel under high pressure directly into the cylinder when the other valves have closed. The effect: even at low speeds, the engine has a rich supply of oxygen and provides an impressive torque. In other words, you can cut back on engine capacity – if you use sophisticated technology.

Audi’s development engineers have turned to downsizing in order to reconcile fuel consumption, environmental impact, and driving pleasure. The principle: a reduction in the engine volume and number of cylinders, while fuel consumption drops as a result of lower frictional losses. At the same time, the turbocharger or compressor ensures solid performance – thanks to technical highlights such as direct fuel injection and variable valve timing. This concept is allowing Audi to make petrol engines fit for the years to come. “Given the technology available today, the thing that makes most sense from an environmental perspective is to enhance the internal combustion engine”, says Axel Eiser, Head of Petrol Engine Development at Audi. “To achieve this, we are adopting a downsizing strategy, the approach which in our opinion offers the greatest potential.”

The star performer among the new generation of engines is the 2.0 TFSI. Depending on the precise version concerned, the four-cylinder engine offers more than 100 PS per liter of engine capacity. At the same time, it demonstrates that the concept of downsizing in fact comprises a number of different innovations: for example, it is the first large-series turbocharged direct injection petrol engine in the world.

FUEL CONSUMPTION DROPS BY ABOUT 20 PERCENT
In addition, this latest step in the evolutionary process offers the new Audi Valvelift System, which uses two cam profiles for variable valve timing, pulling the air into the combustion chamber at low engine speeds as already described. As a result, the engine delivers its maximum torque of 350 newton meters to the crankshaft at only 1,500 revolutions per minute. This is an absolute record for vehicles in this engine capacity class, and one that puts even substantially larger conventional six-cylinder engines in the shade. What’s more, fuel consumption drops by about 20 percent at the same time. And the new models also have a longer gear ratio, which ensures fuel-efficient transfer of power to the drive wheels at lower engine speeds. Launched in the market in 2004, the 2.0 TFSI has won the hearts of customers and industry audiences alike: the Group has already fitted the technology in more than 2.2 million cars, while leading international motor journalists have voted the four-cylinder engine the “International Engine of the Year” four times in a row in its size category since it was unveiled.

Andreas Bach shares their enthusiasm: for several months now, the freelance architect from Munich has been driving the latest two-liter A4 Avant model every day on his visits to building sites and customers. In addition to the ample room provided by the estate, he is particularly happy with the engine: “The car accelerates powerfully at low revolutions and goes easy on fuel”, he says. “The combination of these two features makes for a great deal of fun, especially when you’re out on the road a lot.”

“The larger the engine capacity, the greater the potential savings offered by the new technologies.” Axel Eiser, Head of Petrol Engine Development at Audi (quotation)
Audi A3 1.4 TFSI, Audi A6 3.0 TFSI, The Audi TT (photo)

Clean and fuel-efficient as never before

Audi currently has a large number of models in its range that already comply with the strict Euro 5 emission standards (scheduled to come into force on September 1, 2009). From the Audi A3 1.4 TFSI, which has 125 PS (92 kW) but only emits 140 grams of CO2 per 100 kilometers, to the Audi A6 3.0 TFSI with 290 PS (213 kW), which produces a competitive 219 grams. The Audi TT shows that sportiness and environmental awareness can go hand in hand: even in its most powerful TTS version, with 272 PS (200 kW), the coupé only emits 188 grams. All in all, Audi currently has 95 Euro 5 models on offer – more than any other automaker

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