Allegations of cheating on pollution standards have reached U.S. automakers as Chrysler was sued by consumers who said engines in some Dodge trucks were rigged to hide the fact that emissions were as much as 14 times higher than permitted by law.

The Michigan-based unit of Fiat Chrysler Automobiles NV is the first U.S. carmaker to be sued by consumers. Similar claims were made against German carmakers.

Chrysler and its diesel technology partner Cummins Inc. hid from consumers that pollutants that were supposed to have been broken down inside the diesel engines instead had a tendency to escape, almost doubling the emissions and reducing the vehicle's fuel efficiency, according to the lawsuit. The companies are accused of fraud, false advertising, and racketeering in the complaint, filed Monday in federal court in Detroit on behalf of the owners of almost 500,000 Dodge Ram trucks.

"The sheer level of fraud and concealment between Chrysler and Cummins is unconscionable, and we believe we have uncovered a deeply entrenched scheme," Steve Berman, a lawyer for the plaintiffs, said in a statement. "Chrysler and Cummins spent years lying through their teeth and making empty promises to deliver the cleanest trucks on the market - lip service to deceptively dominate what they saw as a profitable market."

The lawsuit against Fiat Chrysler - created in 2014 through the merger of Chrysler and Fiat - further calls into question the credibility of clean-diesel technology. Excessive emissions from the vehicles exposed the general public to noxious levels of smog, according to the consumer complaint.

The claims involving Dodge Ram pickups from 2007 and 2012 predate the first known sales of emissions-cheating vehicles by Volkswagen by two years.

Cummins increased its research and development budget by 60 percent from 2002 to 2007 to $321 million, about a quarter of which was dedicated to meeting the new standards. The outcome, though, was a flawed engine with limited capacity for trapping excess emissions, according to the complaint.

Shawn Morgan, a spokeswoman for Fiat Chrysler, declined to immediately comment on the lawsuit. Cummins also declined to immediately comment.

Diesel engines, while more fuel-efficient, produce greater volumes of nitrogen oxide pollutants, or NOx. Cummins' engines had limited capacity to store or dispose of the NOx. Instead of NOx being broken down in a process called regeneration, the pollutant had a tendency to escape from the vehicle, sometimes nearly doubling emissions and reducing the vehicle's fuel efficiency as much as 4 percent, according to the complaint.

The process concealed the true emissions output and wore down the car's catalytic converter, which could cost as much as $5,000 to replace.

The companies failed to disclose the engines' shortcomings, which would have prompted drivers to reconsider Chrysler's marketing and ultimately the value of the vehicles, according to the complaint. The suit seeks reimbursement and damages for truck owners.