By William Boston
BERLIN -- Volkswagen AG's emissions-cheating scandal could involve more vehicles than previously acknowledged, and some new models built to meet the most stringent European emissions standards may still cheat, according to a European Union research body.
A report by the European Commission's Joint Research Center, assessing tests conducted in August on several diesel-powered vehicles, also cites elevated emissions on models from Ford Motor Co. and Citroën of France.
The report concludes that a luxury compact car built by Volkswagen's Audi unit produced higher nitrogen oxide emissions outside of routine test conditions, which experts say could indicate use of a defeat device.
The new findings mark a significant new twist in the Volkswagen emissions-cheating scandal because they suggest Volkswagen and its subsidiaries may have installed defeat devices on more engines than previously acknowledged and some new models may still be built to dupe emissions tests.
A spokesman for Audi said the company cannot comment because "we have no information about the study." He said the Audi model in question "performed well" on other independent tests, a reference to tests by the Germany's KBA motor vehicle association.
The EU research center's report also provides data showing that a Citroën C4 Cactus BlueHDi diesel and a Ford Fiesta GDI diesel exceeded legal limits for NOx emissions.
A Ford spokesman said: "Ford does not have what are commonly known as 'illegal defeat devices' in our vehicles, and our advanced diesel engines meet all applicable emissions requirements."
Citroën didn't immediately return requests for comment.
A spokeswoman for EU Industry Commissioner Elzbieta Bienkowska said the center's report was "still under internal assessment," adding that the commission would alert national regulators if "the test results raise some suspicion of wrongdoings." The European Commission is the EU's executive arm.
The EU research center's test results contradict findings by the German government, which passed the Audi model in its official report published in April.
Berlin hasn't yet complied with an EU demand to provide all data from the KBA tests. Brussels last week threatened to take Germany and other member states to the European Court of Justice for failing to provide the data.
The EU research center report, which has been reviewed by The Wall Street Journal, was only recently provided to the European Parliament's emissions investigation committee, or EMIS. It hasn't been published and was first reported by Germany's Sueddeutsche Zeitung newspaper.
The center's tests found that Audi's current A3 2.0 liter diesel, equipped with the EA 288 TDI engine, the successor to Volkswagen's original EA 189 "clean diesel" engine at the center of the diesel scandal, produced higher NOx emissions under certain conditions.
European emissions regulations, called Euro 6, say passenger cars may not produce more than 80 mg of NOx per kilometer. During the center's tests, the Audi A3 came in below that target during a normal "cold start" as is routine in the test.
But NOx values surged when the center's testers veered from routine test procedures, a method that has become common in the wake of Volkswagen's admission last year of rigging nearly 11 million vehicles world-wide to cheat on emissions tests.
When the technicians restarted the Audi A3 after first warming up the engine, a so-called "warm start," NOx values rose to 163 mg/km, twice the legal limit.