BMW and Audi have both agreed to retrofit older diesel-engine cars with software that will reduce their emissions, as Mercedes embarks on its own £195 million service action.

Audi and BMW claim their measures could reduce nitrogen oxide (NOX) emissions by 20% over the next five years.

The BMW Group focused on Euro 5 models issuing a statement which said: “This upgrade incorporates knowledge gained in the field over the last years to realize further improvements in emissions. We deem this to be a part of a comprehensive and joint plan of measures involving municipalities and the industry, to further improve inner-city air quality without across-the-board driving bans, within the context of the ‘Diesel Summit’ on 2 August 2017.”

Audi is targeting customers with Euro 5 and Euro 6 diesel engines. It says a total of up to 850,000 cars worldwide with six-cylinder and eight-cylinder diesel engines will get new software.

In a statement it said: “This will further improve their emissions in real driving conditions beyond the current legal requirements.”

The service also applies to the Porsche and Volkswagen models that are fitted with the same types of engines and will be carried out free of charge for all customers.

Mercedes-Benz announced its own ‘voluntary recall’ last week in which all Euro 5 and Euro 6 diesel engines registered in Europe between January 2011 and September 2015 are eligible.

The £195 million programme is the largest manufacturer-led operation to reduce diesel emissions since Volkswagen pulled 11 million vehicles off the road over the so-called dieselgate scandal.

We will have more on this story in the next edition of Fleet News.