Audi pushes diesel power into US

While Porsche was about to unveil its new Cayenne Turbo, a supercar in a SUV's body, Audi had its own 500bhp SUV on display and though it was lumbered with the 'concept' tag, the Q7 V12 TDI is perhaps more significant to the American market than the showroom-ready Cayenne.

The big difference between the two huge SUVs is that the Audi is powered by a diesel-fuelled engine, which, until very recently, was not really accepted in passenger cars by American buyers. Times they are a changin' though, as US buyers realise that spiralling fuel prices potentially mean an end to the traditional 'gas-guzzling' V8. However, buyers still want performance to go with their fuel economy, so high-performance diesels could well offer a good compromise.

One of the biggest hurdles facing the car makers is tough emissions laws, especially in California. However, Audi has tied up with Mercedes-Benz to develop a new emissions treatment system christened Bluetec. At the heart of the Bluetec technology is a catalytic converter called Selective Catalytic Reduction (known as SCR). Along with this is an auxiliary tank which contains a carbonyl diamide solution, which is injected in small amounts into the exhaust. This in effect breaks down nitrogen oxides into harmless nitrogen and water.

Audi is in a good position to promote the benefits of diesel propulsion. The company made history last year by winning the Le Mans 24-hours race in its new R10 TDI racer and then went on to dominate the American Le Mans Series. The Q7 V12 TDI concept builds on that success by offering an SUV with incredible performance from a diesel engine, yet low emissions and (relatively at least) good fuel economy.

Though not quite ready for US showrooms, the concept does raise awareness for the Q7 3.0 TDI that is likely to go on sale in America later next year.

Tuesday January 9