Fiat Chrysler Automobiles discussed using illegal software to cheat emissions tests in diesel versions of the Jeep Grand Cherokee and Ram EcoDiesel pickup as early as 2010, newly revealed documents show.

The emails, which were unsealed last week as part of a proposed class-action lawsuit against FCA show the company was interested in using software to detect emissions testing on its diesel vehicles to bring them into compliance on the test, according to reports in Bloomberg and Automotive News (subscription required).

The lawsuit claims that Fiat Chrysler misled buyers of those diesel models by touting their fuel economy and performance when they didn't meet emissions standards.

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

2014 Ram 1500 EcoDiesel, Bear Mountain, May 2014

The 2010 emails, from Sergio Pasini, the controls and calibration director for supplier VM Motori, which supplies the V-6 engines for the Ram and Grand Cherokee EcoDiesels, said that Fiat Chrysler was interested in using software that would detect test cycles so it could advertise a 30 mpg highway fuel economy rating for the Grand Cherokee.

The software, known as "t_engine," "is, no matter what Fiat says, a cycle detection," Pasini wrote.

In a response emailed to Bloomberg, Fiat Chrysler wrote: "We continue to cooperate with various governmental investigations related to diesel emissions, and emails such as those referenced have been previously provided to the agencies. It is inappropriate to draw conclusions from isolated communications and internal deliberations without more detailed context that is part of the reviews FCA is conducting as part of the investigation process."

Green Car Reports reached out to an FCA spokesman for further comment but hadn't yet heard back.

DON'T MISS: FCA can settle Jeep, Ram EcoDiesel emission case with fine, recall: Justice Department

The Justice Department sued Fiat Chrysler last year over claims that the company's diesel engines used so-called "defeat device" software to circumvent EPA emissions tests. The EPA also held up certification of 2017 Ram and Grand Cherokee EcoDiesel models.

In January, the Justice Department offered Fiat Chrysler settlement terms that would include recalling all 2014-2016 models equipped with the EcoDiesel V-6 to update their emissions software and bring them into compliance, as well as paying a "very substantial fine (that would) adequately reflect the seriousness of the conduct that led to these violations," according to another Bloomberg report. The fines could amount to as more than $4.4 billion.

The settlement would not require VW-style buybacks, however.

2014 Jeep Grand Cherokee EcoDiesel, New York City, Jan 2014

2014 Jeep Grand Cherokee EcoDiesel, New York City, Jan 2014

In the settlement letter revealed to Bloomberg, the Justice Department referred to "compelling evidence" that the company knew or had reason to know that its vehicles did not comply with emissions standards.

Bloomberg noted that the company had replied in a term sheet that civil penalties would be needed to settle the criminal complaint. The class action lawsuit would be an additional concern for the company.

Fiat Chrysler has denied intentional wrongdoing and CEO Sergio Marchionne referred to the initial complaint last year as "hogwash."