Volkswagen has denied claims that another one of its diesel-powered automobile engines is using hidden software to cheat on emissions tests. The US Environmental Protection Agency filed a notice of violation of the Clean Air Act earlier today, claiming a 3-liter diesel mill used in a variety of VW, Audi, and Porsche models also uses a so-called "defeat device" to cheat on regulatory tests, as is the case with a 2-liter engine in some 11 million Volkswagen vehicles worldwide. In an online statement, Volkswagen says that "no software has been installed in the 3-liter V6 diesel power units to alter emissions characteristics in a forbidden manner."

The news of yet more cars embroiled in the Volkswagen emissions scandal marks a new set of potential complications for the German automaker. Volkswagen is only just now beginning to calculate the full cost of its misconduct, which could hit nearly $90 billion, after CEO Martin Winterkorn stepped down in September. If the scandal widens to include another engine, the consequences could increase dramatically. The 3-liter engine is found in around 10,000 US vehicles, but many more cars in Europe where diesel sales are higher. Yet Volkswagen seems confident the EPA has misunderstood some aspect of its 3-liter engine. The company did not disclose the root of the misunderstanding, but stated it would cooperate with the EPA to clarify the situation.