It’s the latest twist on the Volkswagen emissions scandal: The U.S. Environmental Protection Agency on Monday accused the company of installing so-called defeat-device software on SUVs and additional luxury cars not previously implicated in the scandal, including luxury Audi and Porsche models, according to several reports.

The new allegation cast doubt on the company’s past statements about the situation, since the EPA first accused the company of cheating emissions regulations on diesel cars on Sept. 18.

The additional vehicles could expose the automaker to more than $375 million in Clean Air Act penalties—on top of the $18 billion in penalties the company could incur from the diesel car violations, said USA Today.

"We have clear evidence of these additional violations and we thought it was important to put Volkswagen on notice and to inform the public," Cynthia Giles, assistant administrator for EPA's Office of Enforcement and Compliance Assurance, said during a conference call.

Volkswagen engineers took a sneaky approach when fitting these vehicles with the "defeat device" software, the EPA alleged.

The latest revelations could turn into an existential threat against the automaker, despite recent reports that the scandal ultimately would not cause serious long-term financial damage. That’s now debatable.

Volkswagen, of course, has precious time to respond to the EPA’s latest allegations. A visit to Volkswagen’s official website a few minutes after close of business found no mention of said allegations.