Audi says 2.1 million cars had software to cheat emissions

The announcement clarifies Audi's role in the diesel emissions scandal roiling its parent company, Volkswagen. The Germany automaker admitted last week to installing the software in some 11 million cars around the world; that figure includes the 2.1 million Audi cars, spokesman Jürgen De Graeve said.

Around the world, the affected Audi models include the A1, A3, A4, A5, A6, TT, Q3 and Q5, but the scope was more limited in the United States, where diesel cars are less popular.

About 13,000 of the cars were in the United States, where only the A3 model was affected, Audi USA spokesman Brad Stertz said.

This isn't the first time Audi has faced a massive scandal because of trouble with its cars. In 1987, the automaker was forced to recall more than 250,000 cars because they accelerated unexpectedly.

Audi's sales in the U.S. tanked after the revelation, and it took more than a decade for them to rebound, highlighting the challenge Volkswagen and its luxury brand could now face as it tries to win back customers' trust amid a scandal centering on deception, Deutsche Bank analysts wrote in a research note last week.

"Back in the days, Audi suffered a massive loss in reputation and this wasn't even about cheating," the analysts wrote.

Volkswagen shares plunged on Monday, falling eight percent in afternoon trading. About two-fifths its stock market value has been wiped out since the scandal erupted.

The potential cost of the scandal to Volkswagen is still unknown, but it is expected to be staggering for the world's largest automaker.

It could be subject to up to $18 billion in fines from the EPA alone and is under investigation by the Justice Department.

Government officials in Germany and other parts of Europe have launched separate probes, including one into its former chief executive, Martin Winterkorn, who resigned last week.

Reuters reported Monday that the company has suspended staff from some of its divisions, including Audi, Porsche and Volkswagen.