What's in a name? $10,500 is all

By DAVID LINKLATER

Exactly 12 months ago Mitsubishi Motors New Zealand (MMNZ) launched an all-new version of its Pajero off-roader.

The least expensive five-door petrol model was called the GLS and it was powered by a 3.5-litre GDI V6 engine. It's still available today and costs $75,300.

Last month MMNZ launched another petrol-powered Pajero. It's also a five-door wagon called GLS, but under the bonnet there's a 3.5-litre MPI V6 engine instead.

The new Australian-specification model has manual air conditioning instead of automatic, doesn't have a rear differential lock and misses out on a hard spare wheel cover and side steps, but otherwise carries identical standard equipment to its sister car.

Here's the most interesting bit: MMNZ has announced that the process of changing two letters in the Pajero powerplant's name has slashed a huge amount of money from the car's price.

The new GLS MPI costs just $64,800 - or $10,500 less than the GLS GDI.

Very confusing. And won't all of those Pajero GDI owners be upset about spending all of that extra cash for no reason?

Well, they might have liked the choice right from the start, but GDI buyers are benefiting from leading-edge petrol engine technology, and that never comes cheap.

MPI owners, on the other hand, are getting an ultra-competitive purchase price in return for choosing a conventional powerplant.

Multi point injection (MPI) is the most widely used fuel system among modern petrol engines. The fuel is injected into each intake port, where it mixes with air before it enters the cylinder.

It's very efficient, but Mitsubishi says that there are difficulties in fuel supply response and combustion control because the cocktail of fuel and air is already made when it enters the cylinder.

The gasoline direct-injection (GDI) system works in a similar fashion to the latest generation of diesel engines. The petrol is injected directly into the cylinder with precisely controlled timing.

Combustion characteristics can be instantly modified to be ultra-lean or very rich depending on the kind of driving. Engine emissions are also dramatically reduced.

In practical terms, one GDI engine can deliver diesel-like economy or MPI-beating performance - though not simultaneously.

Mitsubishi claims that a GDI powerplant uses 35 percent less fuel than the equivalent MPI unit at low speed, or 40 percent less in city idling.

But the Pajero's 3.5-litre GDI engine also pumps out 149kW and 318Nm - 9kW and 15Nm more than the MPI powerplant.

Under normal driving conditions the GDI engine operates in economy mode, with an ultra-lean fuel/air mixture and ignition occurring at the latter stage of the combustion stroke.

But when the GDI engine is under heavy load a cooler mixture is injected during the intake stroke.

Four features make up the foundation technology for GDI: an upright straight intake port for optimum airflow into the cylinder, curved-top pistons to accurately shape combustion, a high-pressure fuel pump for precise injection and high-pressure swirl injectors to control the dispersion of the fuel spray.

The GDI is a very smart engine. But it's also expensive technology.

Fill the Pajero's 90-litre tank once a week and even with a best-case 35 per cent improvement in fuel economy it will still take six years of driving to recoup the extra $10,500.

The Pajero MPI, on the other hand, seems to be a very smart move for MMNZ. The company says that it wants to use the new model's sharp price to topple Toyota off the top spot in the large off-roader sales charts.

Previously, MMNZ had no real rival for the price-leading $64,900 Land Cruiser Prado RV.