The big attraction

More than anything else, the all-new in-line six-cylinder turbo-diesel engine is the big attraction on the 330d. With its third generation common rail injection with piezo injectors operating at pressures up to 1800 bar and turbocharger, it now develops 180kW at 4000rpm and 520Nm at a low 1750rpm, figures that should allow for the claimed 6.1-second sprint from zero to 100km/h.

So as far as credentials go, the Beemer 330d and Audi 3.0 TDI are more or less even, but the Beemer does have an efficiency advantage. The 330d manages 5.7 litres per 100 kilometres with a CO2 level of 152 grams per kilometre, easily outperforming its rivals with 6.9 and 183 for the A4, and more so the 7.2 and 191 for the Merc. Now that?s big, and mainly due to BMW?s EfficientDynamics technology, levels that also surpass all other competitors of comparable output.

The all-new 3.0-litre engine is so effective it feels no different to a top petrol engine, revving as freely as one, too, and better than both rivals here. Its just-over 5000rpm is reached with consummate ease. In design terms it?s different than before with the newly developed crankcase of high-strength aluminium-silicon alloy.

That almost dizzying engine performance is thanks to the newly sized crankshaft that reduces frictional losses while the redesigned combustion chambers, valves and inlet tracts not only improve flow but also ensure cleaner combustion. But the big news is the use of ceramic spark plugs to improve starting properties, fuel consumption and exhaust emission levels during the warm-up phase. To top it all, the engine weighs five kilograms less than the previous engine.

Other improvements include all auxiliary units being driven by a single belt to reduce frictional losses and a new third generation injection system with centrally located piezo injectors operating at a high maximum pressure of 1800 bar. Also in place is the new turbocharger with adjustable turbine geometry for spontaneous response at low engine speeds as well as at full throttle.

Audi's gem

The 3.0-litre A4 diesel is also quite a gem and it comes 4kW close to matching the BMW?s output figures, but in torque terms it is 20Nm off. Also assisted by a third generation fuel injection system, its pressure of up to 1650 bar is somewhat lower than the BeeEmm?s. The variable turbine geometry turbocharger is located snugly in the V between the cylinder heads and cooled by an air intercooler placed transversely ahead of the radiator.

However the 320 CDI V6?s quad-cam turbocharged diesel engine doesn?t really match up to its two rivals with its 165kW, but in torque terms doesn?t do to badly at 510Nm. The Merc too, has a third generation common-rail direct injection system with piezo injectors the pressure is the lowest of the three rivals at 1600bar, 50 less than the A4. At just 97kW per litre it just doesn?t compare with the 106 of the Audi and 109 of the BeeEmm ? due also to its corpulent 1765kg mass.

> Who wins the battle? See page 3...