BRUSSELS (AP) — Here's the main thing the United States and the European Union's auto emissions tests have in common: holes so big that manufacturers could, so to speak, drive cars through them.
U.S. regulators only caught on to the fact that Volkswagen was cheating on the tests thanks to help from researchers at a university.
While there is no proof that Volkswagen used the same software to get past tests in Europe, authorities claim they had no idea that millions of cars had the ability to do so.
As the scandal grows, here is a look at what the EU, where Volkswagen has its base in the German city of Wolfsburg, is doing to check cars and how it plans to change.
Q: What is the biggest difference between the United States and the EU in regulating the car industry?
A: It is that while the U.S. has a single authority enforcing rules, the EU has 28.
While rules for emissions are the same for all EU nations, the executive European Commission in Brussels has no powers to enforce them on companies. That is left to each nation's regulators, which may be more or less stringent.
For any of its failings in catching Volkswagen's cheating, the U.S. Environmental Protection Agency has more powers to intervene, and often does.
"The EPA is a strong agency willing to take action as we have seen in the past in different areas," including car safety and fuel consumption, said Johannes Kleis from the European consumer protection body BEUC.
Q: Who sets emission limits in Europe?
A: Proposals on emissions targets are drawn up by the Commission with the input from experts, environmental groups, consumer associations and the carmakers themselves. Then they are negotiated between the 28 member states and the European Parliament.
Talks are being held to improve the system amid allegations the car industry has excessive leverage on the decision-making process. Diesel car manufacturers and relevant industry associations employed 184 lobbyists in 2014, including 51 who were given access passes to the European Union's Parliament, according to environment group Greenpeace.
Q: Who conducts the EU emissions tests?
A: Unlike the United States, emission tests on new vehicle types can be conducted by private companies in the individual member states. National ministries or public agencies choose these companies to carry out the tests on the basis of EU criteria. The results are then sent back to the ministries or agencies, which then endorse a car or van category based on those tests. Car models are not tested again.
Software of the kind Volkswagen used to cheat in the U.S., called "defeat devices," has been banned in the EU since 2007.
Q: Where are the tests carried out?
A: Carmakers can choose the country where they want the tests to be conducted. 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 as well. Currently, most tests are carried out in Germany, home to Volkswagen and Audi, among other high-profile manufacturers.
"There are indications that there is some kind of shopping," said Johannes Kleis from the European consumer protection body BEUC. "Companies choose testing organizations which are more likely to be lenient. There is a certain level of conflict of interest between getting the contract to test the cars and certifying that the cars are in order."
Q: What kind of testing is done?
A: Cars are required to meet emission limits "under normal conditions of use." In practice, this is currently done in laboratories, where emissions are often tested while the car motor idles or turns at low revolutions. The European Commission realized in 2010 that lab tests do not reflect on-road use and a new system is to be introduced in January 2016.
Lab tests are easier to pass as carmakers are allowed to use a so-called "golden vehicle," individual cars that are specially prepared for the test. They are stripped of excess weight and tape can be used to seal up door and window frames, reducing drag. Brakes can be wound off to make sure they don't cause friction, or batteries charged up and alternators disconnected to lighten the load. On-road testing is likely to be more random and so harder to get around.