The dominance of diesel engines in Europe’s new car market could be over before the end of the decade.

That's according to leading automotive engineers, who say a combination of increasingly stringent emissions regulations and the high cost of new-generation anti-pollution technology will make diesel engines much more expensive.

This, say experts, will be coupled with improvements in petrol engine economy and the high possibility of significant rises in the price of diesel fuel. 

Joe Bakaj, head of product development for Ford of Europe, said the costs of meeting the Euro 6 and expected Euro 7 pollution regulations would be a major problem, as would the possibility of reduced petrol refining capacity in Europe. This would force up the price of diesel, a by-product of the process. He also questioned the longevity of the tax advantages of buying diesel in some EU countries.

“Europe exports a lot of petrol to the US, but if the demand falls, a lot of refining capacity could be taken out of the system, driving up diesel prices,” said Bakaj. “There’s also the cost of exhaust after-treatment systems for the upcoming EU6.1 and EU6.2. The latter has more onerous limits on emissions of NOx and particulates.

“It is much cheaper to get petrol engines through EU6.2; with diesel engines we need technology such as selective catalyst reduction systems, and costs increase again with heavier vehicles.”

Bakaj also said petrol engine technology (“which is two to three years behind diesel”) would narrow the gap with diesel on a cost per mpg basis. 

Klaus Schmidt, director of vehicle engineering for start-up Chinese brand Qoros (and previously head of chassis development at BMW’s M division), said he, too, thought diesel engines would markedly decline in importance by the end of the decade, citing ever more stringent pollution regulations as the cause.

Some 50 per cent of new cars sold in the UK are diesels, well behind the 70 per cent in Spain and France, but not far short of the EU average of 55 per cent. Europe is by far the biggest consumer of diesel-powered cars. As recently as 2010, Japan and the US had only a small, single-digit take-up for diesel cars.