The Holden 3.0 V6 produces 190 kW or power at 6700 rpm and 290 Nm of torque at 2900 rpm. Ford's EcoBoost four will reportedly put out 171 kW of power and 325 Nm of torque. The 3.0 V6 comes standard in Holden's entry-level Commodores: Omega and Berlina sedan and Sportwagon and replaces the 3.6 litre Alloytec V6 that put out 175 kW of power and 325 Nm of torque. Economy drops from 10.6 litres/100km in the Omega to 9.3 litres/100 km over a combined city/urban and highway cycle.

But the new SIDI engines are only one part of the major upgrade of Holden's locally produced product. Both engines are matched to a new six-speed auto transmission – code named 6L50 – a small variant of the 6L80 transmission used in Holden's V8 range. In the entry-level Commodores it replaces the sluggish four speed auto and enhances fuel economy and performance. In this Commodore facelift all the changes, except for SIDI badging, are to the drive train.

Holden is the first local manufacturer to introduce direct-injection technology. Multi-point injectors provide direct injection into the combustion chambers, replacing the conventional port-injected engines that inject fuel into the intake port upstream of the intake valve. This allows a higher compression ratio which improves efficiency and performance. Less fuel is used to produce equivalent power. Holden did not release performance figures but the Omega sedan is around about .5 of second faster to 100 km/h and is believed to be around 7.7 seconds. This improvement is largely due to the new six speed auto transmission.

From an Australian perspective the story is really about the 3.0 litre SIDI engine that occupies the engine bay of the volume-selling Omega and Berlina Commodores along with the six speed auto transmission. The transmission gear changes from second to sixth gears and completed with a clutch-to-clutch action where an `on-coming' clutch is engaged and an `off-going' clutch is released to achieve the ratio change.

The SIDI V6 engine is turned to idle at 550 rpm, compared to 600 rpm in the current Alloytec V6, reducing fuel usage at idle. The leaner and meaner Commodores benefit from a raft of other fuel-saving measures.

• A new high efficiency alternator is now smaller and lighter and helps improve fuel economy by reducing generator load.

• Regulated Voltage Control allows greater use of the battery as it monitors the state of charge, allowing power to be drawn from the battery rather than the alternator under some conditions.

• GM Holden has introduced lower rolling resistance tyres from Bridgestone as standard on Model Year 10 with 16 and 17 inch wheels – Omega, Berlina and Calais sedan and Sportwagon models and Statesman.

• When decelerating or coasting downhill, fuel supply to the engine is cut off sequentially to each cylinder. Fuel is seamlessly reinstated when needed. (This was introduced with VE Commodore).

• A turbine damper allows the engine to operate in low rpm, high-torque range where it is most efficient without exceeding noise, vibration and harshness standards.

The combined effect of the improvements results in fuel economy savings between seven and 13 per cent across the VE Commodore and WM V6 SIDI range. CO2 emissions have also improved between seven and 12 per cent. GM Holden claim annual fuel savings of $325 for an Omega owner traveling 20,000 kilometres a year. In general Commodore pricing remains the same apart from Omega and Berlina models that receive a $700 increase on rrp. Omega ute is also up by $700, but now has six airbags as standard.

FIRST DRIVE

We were able to drive both the 3.0 litre SIDI V6 in a Berlina sedan automatic and 3.6 litre Calais V Sportwagon automatic at the launch in `real world' conditions from Melbourne to Lancefield and return.

We did not notice any discernible change to the cars' handling, but the improvement in engine performance and `note' inside the cabin was marked. Under a heavy right foot the engine emits a purposeful growl, unlike the 3.6 Alloytec which was more of an asthmatic wheeze. This new SIDI engine owes a lot to the new six speed auto which is sublime and superbly matched to the smaller V6. The transmission when linked to the 3.0 V6 tends to hunt between fifth and sixth gear when under load, but the downshifts are barely noticeable. The larger 3.6 litre V6 tends to hold the gears due to its larger torque output. In 0-100 km/h tests in the 3.0 litre V6 the engine seems to be doing it easy, once again thanks to the new transmission. The word effortless comes to mind. We also tested the critical 80 -120 km/h passing speed with once again little fuss. The new engine-gearbox combination is far superior to the old Alloytec linked to the four speed. Pushing the Berlina hard we returned 10.4 litres/100 km over 75 kilometres of hilly, winding roads. Our return to Melbourne in the heavy Calais Sportwagon was more leisurely and we returned 8.7 litres/100 km/h without trying in real-world driving conditions.

Day two saw the start of the economy run road test where we drove four legs in four Commodore variations: Berlina 3.0 litre auto, 3.6 litre SV6 ute, six speed manual, 3.0 litre Omega Sportwagon automatic and 3.6 litre Calais V Sportwagon automatic. This was not a straight forward run on the Hume Highway, but a route that took us to Mansfield via Yea, on to Oxley and finishing up at Albury. A mixture of open roads, hill climbs and descents with a few 60 km/h townships thrown in. Most drivers made extensive use of the coasting cut back in fuel on downhill sections – an option available to every new Commodore driver. In sequence we recorded 7.9, 7.8, 7.4 and 7.8 litres/100 km out of the four vehicles. This is an average of 36 miles per gallon in the old money using both the 3.0 litre and 3.6 litre SIDI V6 engines. Given this was primarily open-road testing it makes the model year 2010 Commodore an improved proposition for Australia's rural community. Urban figures are likely to be closer to Holden's official 9.3 litres/100 km. But with some attention to driving style and use of the coasting feature, the new SIDI engines and six speed transmission are streets ahead of the current Alloytec engine and four speed transmissions.