PSA Peugeot Citroën has now built over 10m vehicles with HDi turbodiesel engines since the CO2-reducing technology was introduced in 1998.

The automaker said HDi had it to maintain and expand its leadership in diesel engine technology and to outpace the fast growth in diesel sales in Europe over the past 10 years while making the group the European leader in CO2 emissions control.

Widespread application of the common-rail technology has resulted in the development of a diverse array of diesels, ranging from the 55hp, 1.4-litre I4 engine to the 205hp, 2.7-litre V6. There  are eight passenger car versions and some are shared with Ford group brands including Jaguar and Land Rover.

PSA claims HDi reduces fuel consumption and CO2 emissions by 20% compared with the previous generation of pre-chamber diesels and by 30% compared with a same-size petrol engine.

More efficient management of the combustion process provided by common rail technology has reduced carbon monoxide emissions by 40%, unburned hydrocarbons by 50% and engine particulates by 60%.

HDi technology also enabled the development of the world's first FAP particulate filter, which is gradually being fitted to almost all Peugeot and Citroën diesel models.

"Significant additional reductions in fuel consumption and emissions are still possible thanks to the HDi's potential for further improvements," the automaker said.

The engines are produced in the group's plants in Trémery in eastern France and Douvrin in northern France, and in Dagenham, UK, as part of the cooperation agreement with Ford.