Saab engineers say that six-cylinder engines make up just 20 per cent of the European market for medium-size luxury cars like the 9-3. In the US, however, the ‘entry luxury’ market is dominated by the demand for six-cylinder engines. And with the transatlantic market so important, a big motor is vital.
The new engine
The 2.8-litre turbo unit is based on GM’s new ‘global’ V6 architecture, which will also be the basis for next-generation V6 Opel and Alfa Romeo engines. Although much of the development work was carried out by Holden in Australia, Saab says it was closely involved during the ‘conceptual design and development’, mainly because Saab is GM’s centre of excellence for turbocharging.
The all-aluminium 24-valve V6 powerplant has four chain-driven camshafts, the inlet camshaft getting electronically controlled variable valve timing. Saab says the cylinder heads are unique to its version of the V6. Also unique are the pistons (which are cooled from underneath by jets of oil) and the sintered steel conrods.It gets a high-tech manifold, too. Double skinned and hydroformed (bent into shape by massive water pressure) with stainless steel liners, it is said to help reduce cold-start emissions.
But most distinctive of all is the turbocharger’s installation. A single, twin-scroll water-cooled Mitsubishi unit, it is mounted on the right of the engine above the transmission. Two separate inlet tracts feed it, one from each bank of cylinders. As the exhaust gas pulses alternate between each cylinder bank, the turbo’s twin scrolls get alternating blasts of exhaust gas.
Saab is also very proud of writing its own software for the engine management system, which can limit the engine’s torque output in slippery conditions. That’s useful, because there’s masses of torque. The engine ticks over at 720rpm and by 1500rpm 90 per cent of the twist action is already being delivered. By 2000rpm, the full 258lb ft is on tap, and it is available right around the rev counter until 4500rpm.
Saab says this is its fastest-accelerating production car ever, but with nothing more than a brief drive around Trollhattan we couldn’t confirm this. In six-speed manual form, the official 0-62mph figure is 6.9sec, with a top speed in excess of 155mph.
The only further thing we could glean from Saab’s limited official figures was that the manual V6 can run from 50 to 75mph in top gear in just 8.3 seconds.Sadly, the test cars were US-spec 2006-year models fitted with six-speed automatic gearboxes. The transmission changes gear swiftly and smoothly, but hard acceleration induces a kind of extended slurring reminiscent of a slipping clutch.
Nevertheless, this is certainly a rapid car. Overtaking doesn’t require anything more strenuous than gently extending the ankle. And overtaking is the 9-3 V6’s forte. As you’d expect from the most modern V6 engine available, it is smooth and seamless, but in many ways lacking in character. Admittedly, hooked up to a manual gearbox it could be a very different story, but that won’t improve the dull engine note, despite Saab specially tuning the twin exhaust pipes for a more sporty sound.Were I in the market for a fast Saab, I’d still be tempted by the four-cylinder 210bhp 2.0 T Aero engine, which has an appreciably sharper feel than the V6. Indeed, Saab will still offer this engine in the UK, partly because of its lower CO2 rating (204g/km versus 252g/km for the V6, making for lower company car tax bills).
As hugely competent as the V6 engine undoubtedly is, we will reserve final judgement until we can try the car with a manual gearbox in the UK. But we’re tempted to bet that the V6 is an answer to a question only really being asked in America.