Ford hopes to have the most fuel efficient engine on sale in the US when it adds the 1.0-litre three-cylinder Ecoboost engine to the Fiesta line up. It has just been launched at the Los Angeles motor show

Although the car hasn’t yet been tested by the US’s Environmental Protection Agency, which provides official fuel consumption figures, it should easily achieve over 50mpg. 

It will only be available as the more powerful 123bhp, 143lb ft version that, in the Focus, emits 114g/km of CO2.  

The 1.0-litre Fiesta is set to go on sale in the US next year. No other manufacturer currently offers a three-cylinder engine in the USA.

Dan Stevens