Allegations of cheating pollution standards have reached US automakers as Chrysler was sued by consumers who said engines in some Dodge trucks were rigged to hide that emissions were as much as 14 times higher than permitted by law.
Similar claims have been made against German carmakers. Volkswagen admitted that it installed devices designed to fool emission testing in 11 million cars worldwide in a scandal that may cost it 18.2 billion euros ($19.5 billion).
Claims of rigging vehicles have also been made against Mercedes, which has denied the allegations.
Chrysler and its diesel technology partner Cummins 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 Detroit federal court on behalf of the owners of almost 500,000 Dodge Ram model trucks.
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.
The alleged fraud was prompted by a regulatory shift in 2001, according to the filing. Companies saw an opportunity for growth after the US Environmental Protection Agency announced stringent new emissions standards for heavy-duty diesel engines effective 2010. Chrysler and Cummins bet they could leapfrog the industry and produce a vehicle to meet those standards three years ahead of schedule, according to the complaint.
Cummins increased its research and development budget by 60 per cent 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.
Diesel engines, while more fuel-efficient, produce greater volumes of nitrogen oxide pollutants, or NOx. Cummins's 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.
Rushing to the market to beat competitors was only part of the reason for the fraudulent design, according to the complaint. Cummins also sought to "bank emissions credits to spend on other, dirtier engines," according to the complaint.
VW resolved a major chunk of its dispute in the US in October when a San Francisco federal judge approved a $14.7 billion settlement with drivers intended to get 480,000 cars with polluting 2.0-liter diesel engines off the road by June 2019.
The company is still trying to reach a settlement covering about 80,000 VW and Audi models with 3.0-liter diesel engines. This month, the company was accused in a lawsuit of installing defeat devices on more than 100,000 vehicles with 3.0-liter gasoline engines.
The German carmaker's technology partner Robert Bosch is also accused in the lawsuits of playing a key role in the development of VW's emission-cheating technology.