A particulate filter system is set to play a crucial role in the first high performance, super-clean diesel engine to be built by Renault.

But the equipment designed to burn off harmful 'soot' produced by the four-cylinder, 2.2-litre turbo-charged unit will not involve special additives, according to advanced engineering and research senior vice-president Jacques Lacambre.

“When it reaches the market next year, our filter system will differ greatly from the one offered by PSA Peugeot Citroen,” he says. “Instead of additives, we're using an extra catalyst to burn the soot because we think this is the way to superior durability.”

The latest version of the 16-valve G9 power unit will be offered in the Laguna, Vel Satis and new Espace ranges and will allow Renault to meet stringent Euro 4 emission regulations two years early.

“We are very pleased with the results,” says Lacambre. “Our tests are showing that this unit will provide an improvement in performance of around four per cent with no penalty in operating economy.”

He adds that the only downside is that it will cost Renault significantly more to produce and is therefore likely to be an extra-cost option alongside the current turbodiesel.