That's the prediction of Dr Thomas Weber, head of Group Research and Mercedes-Benz cars development, who says diesel vehicles will need expensive adaptation to meet Euro VI emissions standards being introduced in 2015. The move to Euro V emissions standards has already added costs to the production of diesel cars, with the need for costly fuel injectors and, in many cases, particulate filters.
Weber says: 'Exhaust treatment for Euro VI will add thousands to the cost of diesels in the factory. If, as a manufacturer, you want to be the market leader, you'll need to have a hybrid, too, which will add thousands more.'
The costs that diesel-car production will have to absorb means alternatively fuelled vehicles, such as Mercedes' B-Class F-Cell hydrogen fuel-cell will become more affordable when compared with diesel-powered vehicles.
Although questions remain over the production, transportation and storage of hydrogen, Weber says: 'We are deeply convinced it's an important technology and the right way forward.' While Weber does not rule out other technology, he believes that, in the long term, hydrogen will become cheaper than fossil fuels.
He predicts hydrogen will eventually fall from €8 to stabalise at around €3 (£2.70) a kilo which is enough to travel approximately 60 miles. There are no immediate plans to bring the fuel cell Mercedes to the UK, but 100 customers will soon lease the new Smart Electric Drive in this country.
The Smart is another strand of Weber's future fuel strategy.
2009 BMW X1, which is sold strictly with a diesel engine in the UK