BERLIN (Reuters) -- General Motors' Opel division has denied understating CO2 emissions and fuel consumption after a German television station said the carmaker's own tests on its Zafira minivan had shown strong deviations from official data.
Fuel consumption and CO2 emissions from the Zafira 1.6-diesel version had been found to exceed the carmaker's certified data by 15 percent on average, according to Monitor, a weekly magazine program broadcast by Germany's ARD public-service station.
Three tests of the Zafira conducted by Opel in-house in late October revealed the discrepancies, Monitor said, adding its own tests of a 1.6-liter diesel Zafira conducted at an emissions laboratory in Switzerland had found the model's CO2 emissions exceeded Opel's official data by about 20 percent.
Opel replied in a statement on its German media website: "The CO2 values published by Opel are correct."
"CO2 and consumption measurements are clearly defined by the law," it said, adding its findings on the CO2 levels of its models were monitored by independent inspectors.
Volkswagen's admission to cheating emissions tests for NOx on up to 11 million diesel vehicles and understating CO2 certification data on about 800,000 diesel and gasoline cars has drawn attention to a wider pattern of legal test manipulation that stops short of outright cheating.
Germany's environmental lobby group DUH said in October the Zafira 1.6-diesel had shown excessive NOx emissions, a claim that was denied by Opel at the time.
French rival Renault last month contested findings by DUH that its Espace minivan released toxic diesel emissions 25 times over legal limits in tests carried out on DUH's behalf by a Swiss university.