European suppliers and manufacturers are focusing on petrol engines for the next phase of improvements in fuel consumption and emissions levels.

“The only technology that can accomplish the necessary reduction in fuel consumption — and is also being accepted by customers — is gasoline direct injection,” says Klaus Egger, member of the board at Siemens VDO for powertrain.

While Bosch expects demand for diesel to continue to rise to around 50% by 2007, Siemens VDO believes it has already peaked, and could be closer to 40% in four years.

The key factor in the success of diesels has been the evolution of direct injection systems. While modern diesels inject fuel directly into the cylinder, most petrol engines use port injection, in which fuel is inducted into the cylinder by the valvetrain.

A new generation of direct injection petrol (GDI) engines promise fuel efficiency gains of 15-20%.

Models from Renault, Audi and Alfa Romeo – among others – are already fitted with early versions of GDI and more advanced systems will be available from 2005.

But some industry futurists say petrol direction injection has fallen by the wayside. New engines take a long time to develop, and it will be some years before GDI achieves significant penetration.

Technology leaders in powertrain systems have invested heavily in diesel and electric/hybrid systems over the last decade.

Diesel is about 25% more efficient as a source of energy than gasoline. Over 40% of all new cars sold in Western Europe in 2003 were fitted with diesel engines.

Japan’s carmakers are pressing ahead with hydrogen/electric power as the solution to that country’s unique set of conditions.

Trying to get the best of all worlds

All solutions have drawbacks. While diesel offers improved fuel consumption, other emissions such as nitrous oxides and particulate matter are much more of a problem than with petrol engines.

And for now, the hybrid electric engine faces considerable weight, cost and infrastructure obstacles, especially in Europe and NAFTA.

Cheaper “homogenous” GDI technology will likely find applications in smaller engines, and offers opportunities in downsizing engines for the same power output, resulting in lower carbon dioxide emissions.

These lower cost systems could also “see some penetration in North America, as pressure for improved fuel economy in light truck fleets increases,” says Steve Kiefer, Delphi business line executive for engine management systems.

More sophisticated “spray guided” GDI will initially be developed for engines on premium and luxury sedans, those currently with the worst fuel consumption.

“Our rapid switching piezo injectors will be ready for large volume production by 2005,” says a Bosch spokesperson. Siemens VDO will enter series production a year later.

Magneti Marelli believes GDI could take over 10% of the petrol engine market in 2008. Execu tives at Siemens VDO think it will be closer to 30% of the total petrol market, with the high-end technology alone taking 10%.

Bosch believes that with diesel’s continued growth, GDI will be restricted to only one million units globally in 2008.

But the single largest power source in 2008 in western Europe will still be low pressure port injection petrol systems. Delphi suggests 25-35% of new cars will be so equipped, while Siemens thinks it will be over 40%.

Luigi Potenza, sales manager for Magneti Marelli powertrain, believes alternative powertrains like natural gas and electric hybrids could account for as much as 5% of the western European market by 2008.