U.S. environmental regulators plans to change diesel emissions tests following Volkswagen AG’s admission to fitting as many as 11 million cars worldwide with software to scam pollution testing, the Associated Press reports.

The agency may add testing on the roadways after VW rigged vehicles with technology to let them pass lab tests but emit up to 40 times pollution limits on highways, the AP said, quoting Chris Grundler, director of EPA’s office of transportation and air quality.

Grundler in an e-mail Friday referred questions about the tests to an EPA media call at 10 a.m. regarding the agency’s Volkswagen announcement. He is scheduled to be on the call.

He told the AP that the agency does have on-road testing ability but it’s only been used to check carmaker gas mileage estimates and diesel trucks. -- two situations in which they had uncovered emissions cheating in the past.

The U.S. Justice Department is conducting a criminal investigation of Volkswagen and the company said it’s cooperating with regulators. The admission has marred the reputation of the world’s largest automaker and sent its shares to the lowest levels in years. Volkswagen’s board is expected to name a successor Friday to former Chief Executive Officer Martin Winterkorn to, who resigned this week.

Past Cheating

The scandal now engulfing VW, which has admitted to outfitting cars with software designed to give false readings on emission tests, is unique both for its size and digital complexity. But it’s not the first emissions-cheating case, even for the Wolfsburg, Germany-based company.

On July 23, 1973, the U.S. Environmental Protection Agency accused the automaker of installing defeat devices in cars it wanted to sell in the 1974 model year. VW then admitted it had sold 1973 model year cars with the devices, which consisted of temperature-sensing switches that cut out pollution controls at low temperatures.

General Motors Co. agreed in 1995 to pay $45 million after being accused of circumventing pollution controls on 470,000 Cadillac luxury sedans. The cars’ 4.9-liter V-8 engines were tuned to turn off pollution controls when the air conditioning ran, the EPA said at the time.

The current VW case resembles a 1998 case involving seven manufacturers of heavy-duty truck engines: Caterpillar Inc., Cummins Inc., Detroit Diesel Corp., Mack Trucks Inc., Navistar International Transportation Corp., Renault Vehicules Industriels, S.A. and Volvo Truck Corp.

The companies agreed to spend more than $1 billion, including $83.4 million in penalties, to settle the case -- the biggest civil fine to that point for violating an environmental law.