The Audi A8 can now be ordered with a completely new six-cylinder TDI engine. Costing € 60,500, the A8 3.0 TDI quattro represents the addition of a further sporty version with the characteristics of a long-distance luxury saloon to the A8 range.
The six-cylinder engine in the A8 3.0 TDI quattro develops 171 kW (233 bhp) at 4,000 rpm and summons up an impressive 450 Newton-metres of torque between 1,400 and 3,250 rpm. The lightweight luxury saloon with aluminium body is thus capable of sprinting from 0 to 100 km/h in just 7.8 seconds – a world best for a V6 diesel saloon – and goes on to a top speed of 243 km/h.
The 3.0 TDI is the first production diesel model in the world to have the pioneering common rail fuel injection concept with piezo inline injectors. This permits up to five injection processes per operating stroke and an injection pressure of 1,600 bar.
Piezo technology makes it possible to inject much smaller, more precisely metered amounts of fuel. Thanks to the higher speed of the injector needle, the system moreover responds twice as fast as other injectors. This effect is particularly important for brief intervals between the offset multiple injection processes, of which there may be up to five. The fuel is injected into the combustion chamber via 7-hole nozzles. They, too, play a major part in making the combustion process ultra-efficient and improving the quality of emissions, by distributing the fuel homogeneously throughout the combustion chamber.
The V6 TDI belongs to Audi's new range of V-engines and has a chain drive for camshafts and oil pump. The cylinder spacing in the new engine block is now
90 millimetres. The engine consequently measures a compact 444 millimetres in length. The engine block is made from vermicular graphite cast iron. This is one of the vital clues to the engine's low overall weight of just 220 kilograms – the
3.0 TDI is one of the lightest diesel V6s around. This benefits the power-to-weight ratio and the weight distribution in equal measure – two characteristics that are of central importance for the driving dynamics of the new A8 3.0 TDI quattro.
Further distinguishing features of the engine include four-valve technology with low-friction roller cam followers, turbocharging with two charged air coolers, and electric actuation of the variable turbine geometry, with faster and more precise adjustment of the vanes even at intermediate stages. Particularly at low engine speeds, this builds up the boost pressure faster and thus achieves significantly better responsiveness.
There are likewise continuously variable swirl flaps integrated into the intake tract. They can be used to adjust the air movement according to the prevailing engine speed and load.
All these measures result not merely in high performance potential and an enormous torque plateau, but also in reduced fuel consumption and outstanding acoustic behaviour. Particularly in this discipline, the new engine now unquestionably serves as the benchmark in its class.
And even with 6-speed tiptronic and permanent four-wheel drive, the A8 3.0 TDI quattro – the very first diesel in the luxury class to have controlled, cooled exhaust gas recirculation – undercuts the emission limits of the tough EU4 standard that will apply from 2006. It thus complies with the requirements for tax exemption for a limited period in Germany.
One feature of the new engine that is undoubtedly as welcome as its efficiency at reducing emissions is its impressive fuel economy: the tank dispenses just 8.4 litres of diesel over 100 kilometres (overall fuel consumption).
It therefore comes as no surprise to learn that the new A8 3.0 TDI quattro has an operating range of over 1,000 kilometres on a single tank of fuel.
This is a figure that singles out the sporty saloon with TDI engine as the perfect long-distance vehicle. The first proud owners of the new Audi A3 3.0 TDI quattro will be taking receipt of their cars in April.
Text and photos courtesy of Audi AG
