By Natalia Drozdiak 

BRUSSELS--The European Commission has laid out a proposal to require real-life conditions in testing new cars for the air pollutant nitrogen oxide, sparking a debate among governments over how soon and how hard those new rules should bite.

Following up on a pledge earlier this year by the European Union to improve emissions testing, the European Commission is now pushing for speedy implementation of the new rules following disclosures that Volkswagen AG cheated on U.S. emissions tests.

"Everybody agreed that to convince the consumers, we must really improve the real-life driving emissions rules," said François Bausch, Luxembourg's infrastructure minister, on Thursday after a meeting of European Union transport ministers that discussed the tests

But at issue among member states is the date when the tests measuring a car's pollution in real driving conditions should be enforced and how much leeway should be allowed to miss current emissions limits in order for a vehicle to win certification.

The commission move is a sign that the friendly regulatory environment enjoyed by diesel-engine manufacturers in Europe is coming to a close.

In another signal, French Environment Minister Ségolène Royal said on Wednesday her Socialist government is looking "to equalize" taxes by raising taxes on diesel, which has long enjoyed a lower tax rate than gasoline in France and many other continental European economies, and lowering those on gasoline. She also suggested extra tax revenue could be used as a subsidy to encourage buyers to switch their diesel cars for new ones powered by gasoline.

Under current EU law, cars' air pollutant levels don't need to be tested in real-life situations but only in a laboratory, where auto makers must ensure cars don't emit more than 80 milligrams of nitrogen oxide per kilometer. But lab tests can legally be gamed, and the amount of pollutants emitted in a lab test might be five times less than that found in the exhaust on the road.

The commission on Tuesday presented its plan to a technical group of experts from the bloc's member states, proposing to enforce results from real-life tests starting in September 2017 and allow for 60% higher emissions than the current cap imposed in labs. In 2019, cars would have to fully comply with the 80 mg per kilometer cap on nitrogen oxide emissions, but would be allowed a margin of error to account for technical differences between lab and real--life tests.

The new real-life tests will begin in January but those results won't immediately be used to enforce emissions standards.

Officials said there has been significant resistance to the commission proposal from several governments with large automotive sectors seeking higher margins of error and longer phase-in periods. Large member states, including Spain, Italy and France, have important automobile industries. But a person familiar with the discussions said Germany, with the bloc's largest industry, didn't comment in the meeting Tuesday when the commission unveiled its proposal.

In the wake of the Volkswagen disclosures, Germany may be forced to swallow stricter emissions measures. Mr. Bausch said that "the Germans, they want even to go further now" on emissions.

Before the Volkswagen story broke, officials said Germany had been pushing to delay the implementation period by at least four to five years and allow for cars to emit between four and five times more than the limit during the transition phase.

On Thursday, German Transport Minister Alexander Dobrindt said real-life tests should be implemented "as soon as possible" and enforced after a transition period, but he didn't provide details.

But under the commission's plan, only 10% of diesel cars in current circulation would be able to meet the proposed standards, according to a person familiar with the talks. That means many models would have to be replaced with new types before the normal end of their life cycle.

EU experts have warned about differences in laboratory and road testing for some time. A 2011 report by the European Commissions' Institute for Energy said road tests of 12 diesel vehicles showed nitrogen oxide levels exceeded European limits at times by as much as a factor of 14.

A 2013 follow-up report by the same researchers also pointed to the use of the so-called defeat devices, which are sensors or electronic components that in many modern cars can detect and react to the start of an emissions test in a laboratory.

But due to strong opposition from Germany, Austria, the Czech Republic, Hungary, Slovakia and Poland, it took almost two years of negotiation to agree on the next step when the technical committee finally voted to introduce the real-life tests.

All member states have to respond to the commission's proposal by mid-October. The technical committee is due to vote on the commission's proposal at the end of the month. If they fail to agree, the decision gets referred to ministers.

The realistic conditions of the European tests isn't the only issue. Though it sets the rules, the EU doesn't enforce them and it is up to national governments, which vary in their interpretations, to ensure they are followed.

Jason Chow in Paris and Valentina Pop in Luxembourg contributed to this article.

Write to Natalia Drozdiak at natalia.drozdiak@wsj.com

Access Investor Kit for "Volkswagen AG"

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=DE0007664039

Subscribe to WSJ: http://online.wsj.com?mod=djnwires

(END) Dow Jones Newswires

October 08, 2015 15:44 ET (19:44 GMT)