Audi launches mega-diesel
World's fastest oil-burner delivers 479lb-ft of torque
Audi A8 TDI quattro
Weight has something to do with it. The engine is 15Kg lighter than the 4.0-litre eight-cylinder TDI it replaces, and the compact V8 is Audi's first V8 TDI engine to use common rail fuel injection. It also uses modern piezo injectors, which allow more precisely metered fuel delivery. As a result, power is up by 50bhp at 3,750rpm and peak torque of 479lb-ft is available 200rpm earlier from 1,600rpm, and remains constant for an additional 1,000rpm, up to 3,500rpm.
Featuring a separate high-pressure pump and rail for each row of four cylinders, the piezo system permits up to five separate amounts of fuel to be injected on each working stroke at an injection pressure of 1600 bar, 250 bar more than with previous common rail systems. This helps to achieve the best possible fuel/air mixture and a more efficient combustion process.
Performance is aided by a body shell that, according to Audi, is over 40 per cent lighter than the norm thanks to aluminium construction around the aluminium Audi Space Frame (ASF). Fast gear-changes from the six-speed tiptronic automatic transmission, and secure all-weather power delivery via the quattro four-wheel-drive system, also help the A8 4.2 TDI quattro to power to 62mph in 5.9 seconds, with a top speed of 155mph (limited).
Audi claimed that you get a minimal economy improvement -- 30.0mpg compared to its predecessor's (A8 4.0 TDI 29.4mpg), and up to 590 miles on a single tank of diesel. But if you're paying £60k-plus for a car, how much do you care?
Environmental impact is also minimised by a diesel particulate filter, which is fitted as standard and works in conjunction with the twin catalytic converters to maximise exhaust gas cleansing. The system needs no additives, and so will need no servicing throughout the lifespan of the car.
The new A8 4.2 TDI quattro also sports Audi 's controversial corporate look with its big-mouthed grille. It will offer adaptive air suspension for optimum ride comfort, controlled via the in-car control system. An upgraded SE equipment specification has also recently become a standard feature of V6 and V8 models, and there is now the option to add a new Sport pack available at extra cost.
The car is available in June.
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