Audi shows Q7 V12 TDI with 1,000Nm of torque
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Image Gallery ( 7 images )The trend towards diesel engines is becoming ever more pronounced in the United States too. Audi, the inventor of the modern-day TDI, is going on the offensive in an effort to bolster this tendency. 2008 will see the arrival of the Q7 3.0 TDI in US showrooms. Thanks to the exceptionally low emissions resulting from its cutting-edge Bluetec technology, this engine is able to meet even the most stringent emissions limits.
In Europe, diesel-engined cars have been enjoying an inexorable rise in popularity for years now – in Germany, for instance, they accounted for over 45 percent of new car registrations in October 2006. Today's diesel engines are powerful, fast, efficient, smooth and dependable – virtues which Audi, in its capacity as a pioneer of diesel technology since 1989, has been instrumental in achieving.
The diesel market is also beginning to take off in the USA. In 2006, diesel-powered passenger cars and light trucks secured a market share of around 3.5 percent, and this figure is widely predicted to keep on rising. Firmly convinced that the TDI engine represents the powerful and economical alternative for the future of motoring, Audi is seeking to reinforce this trend: the Ingolstadt brand is embarking on its US diesel initiative.
The stringent legislation governing emissions represents a key criterion for all passenger car engines in the USA. The emission standard entitled US Tier II Bin 8, which is in force in 45 of the 50 US states, limits emissions of nitrogen oxides (NOx) to 0.20 grams per mile and particulate emissions to 0.02 g/mile. The LEVII standard, which is enforced in California and a number of states in the north-east, goes much further again, restricting emissions of nitrogen oxides to 0.07 g/mile and particulates to 0.01 g/mile.
The LEVII limits are simply beyond the capabilities of the emission control technologies required to meet the current Euro 4 standard in Europe.
This is why Audi has teamed up with Volkswagen and DaimlerChrysler to develop a revolutionary new technology – it is called Bluetec and denotes exceptionally clean-running diesel engines.
The Bluetec technology is built around a dedicated catalytic converter which goes under the abbreviation of SCR (Selective Catalytic Reduction) and is positioned downstream from the oxidation catalytic converter and the particulate filter. The second system component is an auxiliary tank containing an aqueous carbonyl diamide solution. The solution, which has been labelled "AdBlue", is injected into the exhaust system in small doses. Once in the hot flow of exhaust gases, it decomposes into ammonia which in turn breaks down the nitrogen oxides into nitrogen and water.
The "AdBlue" reducing agent is routinely topped up at the workshop each time the vehicle is serviced, without the customer having to lift a finger. Audi ensures that there is sufficient "AdBlue" to safely cover the distances between services. Additional benefits include the fact that "AdBlue" is biodegradable and the system's guaranteed effectiveness for the duration of the vehicle's service life.
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