Europe’s diesel debate is heating up as car makers and suppliers compete to market the most environmentally friendly technology, Automotive News Europe reported.

At stake: substantial rewards for those backing the winning technology – and lost revenue and capital for the losers.

At the centre of the discussion is what advanced technology is best suited to trap soot particles in diesel emissions and thus help car makers meet tightening Euro 4 pollution control norms. New no-maintenance systems that don’t require additives are competing with filters whose efficiency is improved by a fuel additive.

Then there’s debate over whether filters are necessary at all. The German car industry has long held that it would be able to solve the particulate problem by improving the diesel-engine combustion process.
And there’s a broader debate: whether despite improving technology diesel engines, which besides soot particles also produce nitrogen oxides or NOx, are inherently more polluting than petrol engines.

Nothing in the debate has dampened strong consumer demand for diesel-powered passenger cars. As a consequence, manufacturers are adjusting their strategies.

Jaguar, whose baby Jag was hurt severely by the absence of a diesel version, corrected that this summer with a 2.0-litre, four-cylinder common-rail version for its X-type. A common-rail V6 from Ford’s collaboration with PSA/Peugeot-Citroen is coming next year. The two diesels mark a major shift for an aristocratic brand that once regarded diesels as alien to its culture.

PSA hopes a diesel particulate filter that lasts the life of the car will give it a competitive advantage in environmentally conscious Germany.

GM Europe misjudged demand for diesels, but has boosted production of diesel-equipped models and is confident it will close the gap with competitors by 2006.

And at next month’s Frankfurt motor show, German car makers will grudgingly introduce particulate filters on several models.

Porsche remains the only German car maker without a diesel. Even its new Cayenne sport-utility comes only with petrol-powered engines.

Suppliers are waging a high-stakes battle to see which is first with new generation high-pressure common-rail injection systems. All this new technology is making diesel engines better and cleaner, but critics still say they continue to be a greater threat to the environment than petrol engines.

“From the point of view of air pollution, soot particles are health problem No. 1,” said Germany’s Environment Minister Juergen Trittin. In an interview with Automotive News Europe’s sister publication Automobilwoche, he predicted that if demand for diesel cars continues at the current pace, particle emissions will triple by 2010.

And diesel popularity is definitely growing in Europe. Diesels captured 38.9% of the new-car market in western Europe last year, but that total rose to 42.3% in the first four months this year, the latest period for which data are available. It is set to grow further.

In Austria, diesels accounted for 72.2% of new car sales in the first four months, the highest percentage in the region. In the major European markets, that percentage was 38.4 in Germany, 67.3 in France and 44.9 in Italy. Even the UK, long a diesel backwater, is converting to diesel because of new laws giving company car buyers tax relief for choosing diesel.

Anti-pollution devices come at a cost and may well have an impact on diesel sales.

“We shall probably see a slowdown in the growth of diesel sales, “ said Louis Schweitzer, chairman of Renault. “The price differential between diesel and petrol engines is likely to increase as new anti-pollution norms come into force,” he told the French magazine Auto Infos.

On average, a car with a medium-size diesel costs about €1,000 more than one with a petrol engine. Because they’re pricier, manufacturers tend to put diesel engines into top-of-the-line models. Anti-pollution devices could add another several hundred euros to the price tag.

Schweitzer believes that this price differential could favour petrol direct-injection engines, a technology Renault and other manufacturers have long been working on.

If direct-injection petrol engines’ fuel economy gains are matched by performance, diesel may start to lose some of its momentum. But for the moment, diesel remains Europe’s premier powertrain.