It was not a very good week for the globe’s largest automaker.

In fact, many upper-tier executives at Volkswagen likely spent much of the weekend sleepless and in close proximity to a bottle of Advil as a public-relations nightmare unfolded for the company in epic proportions.

The gist of Volkswagen’s quandary is that the so-called “clean diesel” technology employed in hundreds of thousands of its vehicles might, well, not be so clean.

In fact, federal regulators and California environmental officials just slapped the German-based vehicle manufacturer with a notice of violation of the Clean Air Act, which could result in an unprecedented amount of pain for the car company. A Los Angeles Times article discussing Volkswagen’s current problems states that the company “could face a fine of about $18 billion.”

That is an eye-popping figure, to be sure, with it being currently unknown what negotiations will ultimately lead to in a settlement.

Federal and California environmental authorities allege that Volkswagen engineers developed technology several years ago that can precisely pinpoint when a vehicle is undergoing formal pollutions tests. At that time, EPA officials say, software inputs “precisely track the parameters of the federal test procedure.”

At all other times, regulators contend, high numbers of Volkswagen’s diesel cars were polluting the environment with dangerous nitrogen oxide gas at a level up to 40 times higher than that authorized by law.

Authorities are now demanding that Volkswagen recall all select models made within a specified-year range and fix them for free. Reportedly, close to half a million vehicles could be affected.

Source: Los Angeles Times, “VW cheated on U.S. pollution tests for ‘clean diesels,'” Jerry Hirsch, Sept. 18, 2015