Micro Micra confirmed

Nissan has joined the throng of European marques adding new and smaller engines to their passenger car lineups with the announcement that its next-gen Micra will be available with an all-new 1.2 litre three-cylinder model, including a very high-tech supercharged Miller cycle version.

The supercharged 1.2-litre three-cylinder engine combines the power of a 1.5-litre four with Euro 6-ready sub-100g emissions, but questions remain over its affordability in Australia

Good for 72kW of power, 142Nm of torque and rated at 95g/km in CO2 emissions, the little mill is the subject of great expectations for the company: the lowest fuel consumption in the world for a mass market petrol burner with performance levels not far off those of the 1.5-litre four that will sit alongside it in the lineup. That engine is expected to produce around 80kW and 148Nm.

The fuel-efficiency/performance mix will come through a high-tech marriage of direct injection, supercharging, and configuration to run to the Miller cycle. This divides the compression stroke into two distinct cycles, boosting the power stroke by delaying closure of the intake valve -- it's often referred to as five-stroke.

The result is a hike in the efficiency with which it converts thermal energy to kinetic energy. The downside is a reduction of pumping effect by the loss of vacuum pressure in the inlet manifold. Hence the supercharger to compensate, and something akin to having one's cake and eating it too.

Part of the key to its combustion efficiency lies in a very high 13:1 compression ratio, achieved by leveraging the cooling effect of the fuel vaporising as it arrives in the cylinder, helped by a piston cooling channel.

In keeping with the trend towards on-demand ancillaries, Nissan has replaced the conventional supercharger drive belt with an automatic on/off clutch which automatically shuts the blower down at low speeds.

With an auto stop/start system cutting CO2 by 6 per cent, the engine achieves a remarkable cut in emissions -- 20 grams below the 115g/km of the Micra's standard base 1.2-litre three-cylinder engine. Performance and economy are helped along by the car's low weight, at around 945kg.

With the new Micra not due for release here until December, the company is still finalising its local lineup. Asked if the supercharged three was on the list, local spokesman Jeff Fisher stressed the engine's antecedents.

"Nothing's out of the question, but it's worth bearing in mind that engine was developed not as a performance option but to comply with increasingly stringent European emissions demands. Not just for Euro 5 but Euro 6 and beyond."

In other words, because Australia is less stringent it will be hard to justify the cost of getting the engine into local showrooms.