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Audi Efficient Drive Systems – Today and Tomorrow



10th September, 2007


Audi is pursuing a consistent strategy to achieve further reductions in fuel consumption and emissions. By the year 2012, Audi will have reduced the CO2 emissions from its models by around 20 percent and in doing so have enhanced considerably their sporty, sophisticated character even further. At the heart of this strategy are technologies from the Modular Efficiency programme and the future-proof TDI engines with ultra low emission system. These are the world's cleanest diesel engines, combining agility and pulling power with excellent fuel consumption figures and unrivalled low emissions. A construction kit with hybrid modules for different vehicle models rounds off the efficiency strategy.

"This underlines Audi's many years in the role of pioneer in developing and marketing cutting edge technologies. We shall continue to bolster the position of the TDI as a highly efficient power system”, explains Rupert Stadler, Chairman of the Board of Management of AUDI AG. “And with our TFSI engines, optimised vehicle architecture and hybrid modules, we shall offer solutions for all standards and all applications, solutions that combine a high degree of drivability with exemplary low fuel consumptions."

Specifically the latest TDI with ultra low emission system confirms again 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, and it thus became 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.

"Audi is the pioneer in the field of diesel technology. We have put the highly efficient TDI technology onto the road more than 4.5 million times since 1989. And with the double victory at the Le Mans 24 hours with the R10 TDI sports car prototype, we have demonstrated in motor sport the degree to which TDI stands for maximum efficiency, drivability and economy, just as we did before on the road," stresses Michael Dick, member of the Board of Management of AUDI AG responsible for Technical Development.

Consistent strategy for all model series

With the latest generation of TDI technology, Audi is demonstrating anew the future compatibility and the potential of this high-tech drive system. The optimised combustion process and an ultra low emission system enable these vehicles to satisfy the valid American LEV II BIN 5 standard and the strictest emissions limits due to come into force in Europe.

Audi will start its systematic TDI strategy in 2008 with the 3-litre V6 in the Audi Q7 and A4. Generating 176 kW in each and with outstanding torque of 500 Nm in the A4 or 550 Nm in the Audi Q7, both models display the supreme dynamics and efficiently low fuel consumptions figures typical of Audi. Additional models will quickly follow. By 2010, Audi plans to offer the new technologies in other vehicles segments and power classes.

Innovative technology for minimum emissions

This new Audi technology elevates the TDI's direct injection principle, a principle that has been proven a million times, to a new level. The engineers in the diesel engine development at Audi have combined a whole package of innovative measures for 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 one highlight. These enable the combustion processes inside the engine to be regulated even more precisely – yet another Audi innovation.

The latest TDI engine ultimately becomes the clean high-tech diesel when it is combined with the ultra low emission system. This reduces nitric oxides by up to 90 percent. This system uses the additive AdBlue, a biologically degradable water-based solution. 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.

Great potential for global reduction in fuel consumption

Thanks to its minimal emissions, these modern direct injection diesel engines can be used anywhere in the world, even in California, where the world's strictest emissions limits apply. 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 percent. This means that diesel technology more than any other current power system can help to reduce the consumption of fossil fuels. Audi will offer these new models in the USA and Europe from the second half of 2008.

Extensive package for reducing CO2 emissions

For Audi, perfecting the TDI is part of the integrated technology strategy for further reducing CO2 and other emissions in all its models. All in all, Audi is relying on the great potential of its modern combustion engines. With direct injection and turbo charging, plus high torque with reduced cylinder capacity and lower losses due to friction, the TFSI spark-ignition engines, like the TDI diesel engines, have the best consumption figures available today.

To reduce them even further in the future, Audi is working on the Modular Efficiency programme, with various modules to be used on future models. Here, many Audi TDI and TFSI engines are equipped with an innovative energy management system, which uses the coasting and braking phases to generate and store electrical energy. At standstill and when accelerating, this energy can be used to relieve the load on the alternator and the vehicle electrical system.

Moreover, a new generation of start/stop system is being developed that will satisfy Audi's standards of comfort. Other elements of the Modular Efficiency programme are ancillaries with optimised power requirements, a newly designed air conditioning system and a gearbox preheating system to increase the efficiency of the transmission. Even today, the optimised tiptronic, the continuously variable multitronic and the S tronic dual-clutch gearbox give Audi a superior range of transmission technology, and this will be expanded and systematically employed in the future.

e-models in the high-volume model series

Detailed precision work, not only in the drive train but also on the complete vehicle, help to achieve further reductions in fuel consumption. Optimised rolling resistance, even better aerodynamics figures, specially configured gearboxes and transmission ratios, and reduced friction are just a selection of modules that Audi is working on to achieve continual increases in the efficiency of the entire vehicle range. With their high torque at low engine speeds, Audio's turbocharged direct injection spark-ignition and diesel engines offer perfect conditions for a gearbox configuration that allows maximum engine efficiency.

Examples for the success of this strategy are the e-models already in series production. Evidence is provided by the current Audi A3 1.9 TDI e with its excellent average fuel consumption of just 4.5 litres per 100 km (combined cycle) and CO2 emissions of 119 grammes per kilometre. In the future, Audi will vastly expand the range of such especially efficient models, offering e-models as TDI, FSI and TFSI in the high-volume model series. From 2009, the technologies that so effectively reduce fuel consumption will be gradually introduced on all Audi models.

Audi also demonstrates its "Vorsprung durch Technik" in the luxury segment: The Audi A8 is not only the sportiest saloon in the luxury class, it is also characterised by it unrivalled efficiency. For example, the new A8 2.8 FSI fascinates with its superior performance and excellent ride comfort. But at the same time, it also has an average fuel consumption of just 8.3 litres per 100 km, and with 199 grammes per kilometre the lowest CO2 emissions in its class. Here, intelligent lightweight construction in the form of Audi Space Frame (ASF) aluminium technology represents another example of the brand's pioneering competence.

Hybrid systems for several models

Hybrid systems may however still be interesting for specific requirements in certain markets. Audi is developing hybrid systems for several model series and will put these into series production wherever substantial benefits for the customer can be seen. Audi sets very high standards for the quality of the hybrid drive – it must rival the efficiency of the latest Audi TDI technology.

Audi is working on the Audi Q7 hybrid, which has an electric motor/generator integrated in the drive train between the engine and gearbox. As a so-called full hybrid, the Audi Q7 can run on either the spark-ignition engine or the electric motor, or combine the power of the two. When it is coasting or braking, kinetic energy is converted to electrical energy, fed back into the battery and converted to forward propulsion as necessary.

Here, Audi has chosen the principle of parallel hybrid – a new solution in this class that has a potential superior to the competition. It 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. This allows Audi to retain its typical handling characteristics, even with a hybrid drive. Moreover, the systematic configuration as a modular system makes adaptation to different model series easier.

Integrated approach for better fuels

Modern fuels will play a decisive role in future reductions in CO2 emissions.

Besides ethanol and natural gas, these are above all the next generation fuels which are synthetically produced from biomass or natural gas. These specially tailored fuels improve the combustion process inside the engine and thus allow a significantly improved energy balance.

SunFuel, made from biomass, is especially efficient. During combustion, this fuel only releases as much carbon dioxide as the plants that were processed into SunFuel previously drew from the atmosphere. If you take the production operations into account, SunFuel is able to reduce the overall CO2 footprint by more than 80 percent. An Audi A3 1.9 TDI driven on SunFuel emits less than 20 grammes of CO2 per kilometre, even taking the entire process chain into account. The first facilities for large-scale production of these fuels are currently being built. Audi provides extensive support for this integrated approach for better fuels, but clear political signals are needed if they are to become widespread.

Alternative fuels

Alternative fuels are gaining in importance all around the world. In many countries for example, natural gas is being used more and more as a low-cost, low-CO2 energy source. Here, Audi has developed a concept for the use of CNG (compressed natural gas). It is based on the TFSI engine and retains the strengths of this engine, for example the great pulling power and spontaneous response, even in natural gas operation.

In other words, CNG operation allows you to enjoy a CO2 balance that is up to 20 percent better, without having to make compromises in driving pleasure. Moreover, the innovative package, despite the natural gas tank, allows full versatility and use of the luggage compartment.

The same thing applies to Audi's ethanol drive. It is designed so that fuels with up to 85 percent ethanol can be used – again without compromising on dynamics or sportiness. However, just how favourable the overall environmental balance of such a system is can only be seen when 2nd generation bioethanol is used.

This can be produced from straw and wood, i.e. from residual materials, and not from energy plants as it is today. In any case, the energy source used and the process employed to produce the fuel is decisive. For this reason, Audi only views hydrogen as an option for the distant future, in association with regenerative energy sources.

The decisive influence of the driver

Audi will continue to demonstrate its "Vorsprung durch Technik" with a wide range of technical solutions for the customer. And despite all this, the driver retains a major responsibility for a driving style that contributes to reduced fuel consumption. Individual driving style can reduce fuel consumption, and with it emissions, by up to 30 percent – without compromising on speed and dynamism.

The decisive factors are the driver's awareness and attentiveness. For this reason, Audi supports the driver with additional assistance and information systems. These help him/her to optimise their driving style with respect to fuel consumption. A first example is the gear shift indicator found as standard on the e-models and on the new Audi A5. This indicates the best gear for the current driving situation.

Especially high efficiency at the touch of a button

In the future, helping the driver to adopt a low-consumption driving style will go a lot further. For example, Audi is working on a navigation system that takes consumption relevant data into account and which gives route recommendations accordingly. The necessary information about road conditions or traffic lights will be available with the next generation of digital road maps.

Similarly, an on-board electronic driver trainer is being developed. This system is able to analyse the current driving style and give tips accordingly.

With the Cross Coupé quattro study, Audi has presented another concept. The driver can select a particularly fuel economical mode at the touch of a button for certain situations.

In "efficiency" mode, the engine and gearbox maps are switched to a low-consumption map, the power draw to the major consumers and comfort modules is limited, and cruise control gives priority to fuel consumption as it regulates the vehicle speed. This mode is consciously selected by the driver and is only associated with slight losses in performance and comfort. Yet it saves about 20 percent fuel compared to "sport" mode.

A clear course into the future

With its integrated efficiency strategy, Audi is systematically working on achieving further reductions in fleet fuel consumption. The combustion engine will remain the major drive system for the foreseeable future. Already an extremely efficient principle, the TDI still has considerable potential for further reductions in fuel consumption, and the ultra low emission system is the guarantee that it remains absolutely future proof.

The TFSI principle and the Modular Efficiency programme will guarantee significantly reduced CO2 emissions for all new model series. Finally, TFSI engines, complemented by hybrid modules, will represent an alternative to the TDI in certain markets.

On this point, one thing is indisputable for Audi, efficiency and reduced fuel consumption will never be achieved at the expense of the brand's other strengths. Audi will retain and enhance its sporty-elegant character, drivability and the high quality standards of its models, even as emissions are further reduced.

Other Audi content: here.

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