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Progressive Performance – An Audi Hallmark

April 3rd, 2008


More driveable, fewer emissions

More dynamism with less and less fuel consumption – Audi is pursuing a consistent strategy of ‘Progressive Performance’ to achieve further reductions in emissions, unveiling three new concepts for the A4 - each of which is virtually ready for series production.

The A4 2.0 TDI e Concept - Just 129 grams of CO2

With the new 2.0 TDI e Concept, Audi has shown the effectiveness of its Modular Efficiency program. The sporty middle class sedan requires just 4.9 litres of fuel per 100 km, equating to CO2 emissions of just 129 g/km – less than the limit that the European Union aims to introduce for vehicle fleets from 2012.

With an output of 105 kW and peak torque of 320 Nm, the A4 2.0 TDI e Concept is also powerful – following Audi’s systematic goal of dynamic character hand in hand with low consumption.

In this vehicle, Audi has realised a whole package of innovative engineering solutions. Some of these are already in series production on the new Audi A4. Others, such as the start/stop system or the energy recuperation system, will be introduced in the near future.

TDI - Efficient and dynamic

The 2.0 TDI available today has been essentially enhanced to achieve TDI ‘e’ status. A common rail injection system supersedes the unit injection pumps used to-date, its piezo injectors supplying fuel with a pressure of up to 1,800 bar, allowing extremely fine atomisation in the combustion chambers, improving combustion and smooth running.

The refined engine develops a powerful 105 kW and even in the speed range between 1,750 and 2,500 rpm it puts a bullish 320 Nm of torque onto the crankshaft. Mighty pulling power at low revs is one of the great strengths of the TDI principle.

Modified piston geometry improves thermodynamics in the combustion chambers while other measures to reduce internal friction and for temperature management further increase fuel efficiency.

On the A4 e Concept, the 2.0 TDI engine is supplemented by an ultra low emission system. That means that this engine not only works very efficiently, but it is also exceptionally clean and absolutely future-proof. Even today, it undercuts the strictest 2014 European emissions levels. Audi’s ultra low emission system, which makes the TDI the world's cleanest diesel, will go into series production in 2008 as an option on the new Audi A4 3.0 TDI.

New stop/start system

Another important contribution to clean-running is made by the start/stop system which neutralises engine inefficiency while the vehicle is stationary. This is especially important where much of the day-to-day driving is made up of short trips (less than 10km), which are further interrupted by numerous stops at traffic lights.

As soon as the A4 2.0 TDI e Concept comes to a standstill, the gear lever is moved to neutral and the driver takes their foot off the clutch, automatically switching off the TDI.. The engine is restarted when the driver depresses the clutch. The TDI runs up while the gear is being engaged. It has reached idling speed by the time the pedal is released. A specially-developed starter motor turns the engine in little more than two tenths of a second – 60% faster than a conventional part, and yet very quietly.

The power steering has also been thoroughly modified and is now 50% more effective as it is now fed hydraulic energy by a demand-controlled vane-cell pump. In contrast to conventional power steering pumps, which constantly recirculate large volumes, it only pumps as much oil as actually needed at that very moment.

On the automatic air conditioning system, Audi uses an innovative, thermostatically- controlled refrigerant circuit with an internal heat exchanger. Along with intensive precision work on other components, this greatly improves efficiency – requiring 20% less fuel than its predecessor.

Aerodynamic to reduce drag

The A4 2.0 TDI e Concept glides smoothly and effortlessly through the wind thanks to its extremely aerodynamic body. The boot lid has been given a slight additional separation edge and specially-designed alloy wheels improve the airflow across the wheels and arches, while sporty tuning has lowered the body by 20 mm.

This modification reduces the frontal area, improving air resistance.

Perhaps the most impressive evidence of the potential of the A4 2.0 TDI e Concept is found in its performance figures. The middle class saloon sprints from 0 to 100 km/h in just 9.3 seconds. Its top speed is 215 km/h. A spurt from 80 to 120 km/h in 5th gear needs just 8.7 seconds.

The Audi A4 2.0 TDI e Concept shows what such a concept could be in the new A4 model series. By the year 2012, Audi will have reduced the CO2 emissions all from its models by around 20% and in doing so have improved their sporty, sophisticated character even more.

A4 3.0 TDI - the world’s cleanest diesel

Audi’s new A4 3.0 TDI with ultra low emission system demonstrates the future-proof potential of the high-tech TDI engine. From mid-2008, the cleanest diesel in the world will be available in the A4. This vehicle is a stand-out performer in many ways, from the dynamics of its 176 kW engine and outstanding torque of 500 Nm, combined with its low fuel consumption and extremely low emissions.

Right from the very start, the car will satisfy the emissions limits due to come into force in Europe from 2014, and the LEV II BIN 5 standard valid in the USA. The cleaning effect of the system is also seen in the levels of NOx nitric oxides, which have been reduced by 90%, and yet it works more effectively than any other technology on the market.

Minimum emissions

Numerous measures have been implemented in the development of this latest TDI generation. The new piezo common rail system with an injection pressure of 2,000 bar, highly efficient exhaust gas recirculation and the optimised turbocharger produce greatly reduced raw emissions. Combustion chamber sensors - a world first - are another highlight, enabling very precise regulation of combustion processes inside the engine.

The ultra low emission system reduces nitric oxides by up to 90% by using AdBlue, a biologically-degradable water-based additive. A minute dose is injected into the system upstream of the DeNOx converter. The ultra low emission system comprises the catalytic converter and a metering module, the AdBlue tank and heated lines, and an extensive system of sensors. The additional oxidation catalytic converter and the highly efficient regulated diesel particulate filter complete the comprehensive exhaust emissions control system.

Global reduction in consumption

Thanks to these minimal emissions, modern direct injection diesel engines can be used anywhere in the world, even in California, where the world's strictest emissions regime applies. Compared to the fleet average for the spark-ignition engines, the most common power system in the USA, the TDI has a consumption advantage of up to 35%, meaning that diesel technology, more than any other current power system, can help to reduce the consumption of fossil fuels.

The latest TDI with ultra low emission system confirms Audi's pioneering role in implementing low-consumption technologies. When Audi put the first TDI into series production in 1989, it was a remarkable milestone in technical progress. TDI rapidly developed into a synonym for supreme pulling power and maximum efficiency, becoming a trendsetter for the entire automotive industry. Until today, no other drive system has managed to beat the turbocharged direct injection diesel for agility and low fuel consumption figures under real-life operating conditions.

Hybrid also under development

In September 2007, Audi presented a drivetrain model with the latest generation of its hybrid drive concept. Because of its straightforward, modular structure, this ‘parallel hybrid’ can be fitted to any Audi model with a longitudinally-installed engine, and can be combined with almost any combustion engine. Audi will put its hybrid concept into series production as soon as this provides decisive benefits for the customer. Of course Audi sets very high standards for the quality of the hybrid drive – it must rival the efficiency of the latest Audi TDI technology.

Parallel hybrid technology is a new solution in this class that is more efficient than any other system currently on the market, especially when driving long distances and on motorways. In addition, its spontaneous response makes sporty-dynamic driving possible, retaining Audi's typical handling characteristics, even with a hybrid drive.

An important basic factor for the high efficiency of the hybrid drive is an extremely efficient combustion engine. The Audi 2.0 TFSI engine is ideal. It is characterised by both a high 155 kW output and 300 Nm peak torque as well as very low fuel consumption. Its opposite number on the electrical side also represents an optimum of efficiency and power density. The electric motor, a permanently excited synchronous motor, develops a further 32 kW of output and a peak torque of 230 Nm practically from standstill.

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