The Volkswagen Group has long harboured high hopes for its sales in the USA, but matching them has proven more challenging than the manufacturer might have wished.

In 2007, it boldly announced that it expected to attain group-wide US sales of 1 million cars per year by 2018, in line with a plan to sell an annual 10m vehicles worldwide by the same year.

For a few years, the plan appeared to be on course, with market-specific models gaining ground against the likes of Toyota, but in recent years the growth has stalled.

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The manipulation of emissions testing in the USA - reported by the US Environmental Protection Agency and seemingly uncontested in a statement made by Volkswagen Group boss Martin Winterkorn – is an incident that could torpedo any prospect of making serious headway in that market for the foreseeable future.

This is especially difficult because it affects VW’s diesel engines. The company has done a great deal of work to boost sales of oil burners in the USA, branding its cars as ‘Clean Diesel’ and trying to break down deep-held beliefs among American consumers that diesels are excessively dirty.