VW emission test cheat scandal expands to subsidiaries Audi and Porsche

German automaker Audi has admitted that it fitted "defeat devices" to 2.1m vehicles to cheat on emissions tests. Audi is a subsidiary of Volkswagen, whose use of the gadgets on some 11m diesel engines was exposed by nonprofit investigators.

The BBC reports that the Audi vehicles were sold worldwide: 1.4m in Europe, 577k of them in Germany, and 13k in the United States. The scandal threatens to destroy the group, but suspicions abound that other automakers are engaged in similar shenanigans.

Meanwhile, Volkswagen shares continue to fall in morning trading, sinking a further 6.6% in addition to last week's tumble.

The scandal has badly tarnished VW's name, left it exposed to up to $18bn in US fines, and wiped a third off its stock market value in a week.

German authorities have demanded that VW set out a timeline by 7 October on how it will ensure its diesel cars meet national emission standards without using cheat technology.

German prosecutors have launched a criminal inquiry into freshly-resigned VW boss Martin Winterkorn, who claims he had no personal knowledge of the devices.

Reuters also reports that sports car division Porsche may be involved.

Sources familiar with the matter said on Monday it had also suspended the heads of research and development at its core VW brand, luxury division Audi and sports car maker Porsche.

But the crisis shows no sign of dying down.

Two German newspapers said on Sunday Volkswagen's own staff and one of its suppliers had warned years ago about the illegal use of so-called "defeat devices" to detect when a car was being tested and alter the running of its diesel engine to conceal their emissions of toxic nitrogen oxides.

"The Volkswagen scandal was just the tip of the iceberg," according to a manager at Transport & Environment, an environmental campaign group that works with the European Commission.