NEW YORK (TheStreet) -- Fiat Chrysler (FCAU) - Get Report stock is decreasing by 1.68% to $12.89 in afternoon trading on Friday, after the U.S. Environmental Protection Agency said it will test vehicles in a normal driving setting, The Walls Street Journal reports.

The EPA will conduct random emissions testing of 2015 and 2016 diesel-powered vehicles and also seek software that would cheat official emissions tests, like the ones used byVolkswagen (VLKAY) .

"We aren't going to tell them what these tests are, they don't need to know," the EPA's Office of Transportation and Air Quality director, Chris Grundler, told The Journal. "They only need to know we will be keeping their vehicles longer and driving them more."

Companies were responsible for submitting their own emissions test results and design certificates because the EPA considered diesel-powered vehicles to be a small share of U.S. vehicles, with less than 1% share in annual sales of new cars, The Journal noted.

The EPA has focused its resources on testing diesel-powered trucks instead.

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