The carmaker has already said that the long-awaited 1.6 diesel, which will deliver 94g/km of emissions in the Civic and an official combined figure of 78.5mpg, will help it gain ground in the lower-medium sector.

Under the latest announcement, the unit will now form the basis for a family of small-capacity diesels as part of a new range of engines that will replace the entire current line-up over the next three years under its new Earth Dreams Technology eco sub-brand.

The 1.6 unit has been described by Honda insiders as its most important new engine in a decade and will soon power a quarter of all its cars sold in the UK, according to reports.

Honda has also said that the diesel – currently Euro-5 compliant – can be made Euro-6 compliant once the content of the new legislation on the Euro-6 standard has been fixed.