Fiat Chrysler CEO Sergio Marchionne told CNBC on Thursday the company is "fundamentally different" from German automaker Volkswagen, following accusations that it used software that allowed excess diesel emissions.
"(The vehicles) do not distinguish between test cycles and running a normal running operation, so the cases fundamentally different, and it is important for us to distinguish ourselves from the current state of the art in this area," he said on CNBC's "Power Lunch"
Earlier on Thursday, the U.S. Environmental Protection Agency accused Fiat Chrysler of using software that allowed excess diesel emissions in about 104,000 vehicles.
The agency alleged the automaker violated the Clean Air Act by installing and failing to disclose "engine management software in light-duty model year 2014, 2015 and 2016 Jeep Grand Cherokees and Dodge Ram 1500 trucks with 3.0 liter diesel engines sold in the United States."
It said it is also investigating whether the auxiliary emission control devices constitute "defeat devices," which are illegal.
The accusations comes after Volkswagen admitted to criminal offences in rigging U.S. emissions tests. It agreed to pay $4.3 billion in civil and criminal fines in a settlement with the U.S. Justice Department.
U.S.-listed shares of Fiat Chrysler plunged as much as 18 percent on Thursday in intraday trading.
Marchionne said the company has been "unnecessarily marginalized" by the EPA, and said the company feels the software is compliant with EPA's standards.
He also said the company has been in discussion with the EPA for a year and a half. Marchionne said the company plans to wait until the new administration takes over to hammer the issue out.
The undisclosed software results increased nitrogen oxide emissions from the vehicles, the EPA said. The Justice Department is reportedly working with the EPA on this issue.
Fiat Chrysler said in a statement on Thursday it is "disappointed" the EPA has decided to issue a notice of violation, and said its engines are "equipped with state-of-the-art emission control systems hardware."