Ford reckons that petrol engines are going to win market share back from diesel engines, and is planning to triple production of Ecoboost petrol engines to meet demand.

The amazing new 1.0 Ecoboost will take the lion's share of the increased output, with the engine replacing most versions of the conventional 1.6 litre petrol engine in the Focus. It will also go into the B-Max small MPV later this year and the Fiesta in 2013.
In 2015, diesel engines will have to meet EU6 standards, which will require additional pollution systems to neutralize oxides of Nitrogen. The good news is that an EU6 diesel will emit no more pollution than an equivalent petrol engine, but the bad news is that it is likely to be a few hundred pounds more expensive than a current diesel engine.

Ford reckons that Ecoboost engines, which broadly halve the fuel economy difference between a conventional petrol engine and a diesel, will take an increasing share of sales. The purchase cost of a diesel will become so much higher than a petrol engine that most buyers of a Ford Focus will not be able to recoup the extra cost of a diesel engine via lower fuel consumption.