Volkswagen diesel emissions probe in U.S. extended to other automakers

The U.S. Environmental Protection Agency has extended its diesel emissions testing to car models made by BMW, Chrysler, General Motors, Land Rover and Mercedes-Benz, according to a report in the Financial Times.

After learning it had been duped by Volkswagen with a "defeat device" that turned on emissions controls only during testing, the EPA is facing scrutiny from both lawmakers and consumers.

• How emissions tests that exposed VW scandal were done
• Volkswagen emissions rigging echoes similar scandals at GM, Toyota, Honda

Millions of Volkswagen's diesel vehicles emit more than the legal limit of nitrous oxide, a gas that has health risks, including affecting brain function. VW has admitted it installed engine software that turned on controls for the gas during laboratory testing but turned them off in real world driving as the controls can reduce gas mileage.

The EPA will test one of each of the 28 diesel models currently on the roads using rental cars or cars obtained from consumers.

The agency is targeting most of the diesel vehicles on U.S. roads, according to the FT, which cited documents it has seen. These include BMW's X3, Chrysler's Grand Cherokee, GM's Chevrolet Colorado, the Range Rover TDV6 and the Mercedes-Benz E250 BlueTec.

• Could Volkswagen scandal be diesel's death knell?
• EPA works with Canadian regulators to retest VW vehicles

These automakers have said their vehicles are not installed with defeat devices, but the VW scandal has tainted the reputation of all diesel vehicles.

In its regular testing regime, the U.S. emissions regulator uses models provided by the manufacturers, which may be different from models sold to consumers.

Flawed testing regime

This is just one of the elements of the EPA testing regime that has been exposed as flawed because of the VW scandal.

The vehicles are tested in labs, meaning the results do not reflect real-world driving conditions.

U.S. regulators only caught on to the fact that Volkswagen was cheating on the tests thanks to help from researchers at University of Virginia, who compared lab results with real-world measurements.

The EPA appears to have relied on European regulators to fully test diesel vehicles, because diesel cars are in much wider use on roads in the European Union.

And that has unleashed a storm of criticism of EU testing, covering everything from the influence of vehicle manufacturers in setting emissions standards to lax enforcement across the EU.

EU testing criticized

While the EPA is considered a very strong regulatory body that is not afraid of pursuing automakers, the EU has 28 separate regulatory agencies, many of whom may be under pressure to protect local car industries.

Rules for emissions are the same for all EU nations, but they are set with the input of automakers as well as experts and consumer groups. There has been criticism over whether automakers have too much influence in the process.

There is also evidence that car companies cherry-pick the regulator they want to test their car.

Because the emissions criteria are set for the bloc as a whole, approval in one country means that type of vehicle can be registered in any of the other 27 member states.

Currently, most tests are carried out in Germany, home to Volkswagen and Audi, which are considered influential companies on a national as well as global scale.

Carmakers also are allowed to use a so-called golden vehicle for testing, which may be stripped of excess weight and have brakes disengaged to lessen drag and improve performance measurements.

Talks are currently underway in the EU to upgrade its emissions standards and testing regimes.

Meanwhile, regulators have sprung into enforcement mode across the EU and are threatening investigations and criminal charges.