Jaguar Land Rover, Lamborghini, Ford, Bentley, the PSA Group and Renault have also denied manipulating the tests through the use of defeat devices or extra software.
Along with a VW Passat and Jetta, a US-specification 3.0-litre BMW X5 was one of three diesel-powered vehicles involved in the initial research project into nitrogen oxides emissions conducted by West Virginia University (WVU), which then relayed its findings to the US Environmental Protection Agency (EPA).
During the tests in 2014, the X5 did not record any emissions readings to concern WVU’s researchers.
A BMW UK spokesman told Autocar: “Regarding BMW’s position, we do not use any software that can influence emissions in the test cycle.
“The International Council on Clean Transportation [ICCT] study which resulted in the EPA investigation showed that the tested BMW vehicle complied with the limits set, including in real-world driving situations. Given the positive results of the BMW vehicle emission test, neither EPA nor CARB [California Air Resources Board] have approached BMW in connection with this matter.”
The spokesman explained that BMW UK’s diesel engines achieved compliance with the latest EU6 emissions standards either by use of a urea injection system – as fitted to the X5 used in the original WVU test – or via engine technology.
“With regard to urea additives, there is a small number of vehicles that we now offer with this technology, namely: 520d GT, 730d and 740d and X5/X6 diesel variants.
“All other BMW diesel engines in the UK achieve the EU6 requirements through measures inside the engine, exhaust gas recirculation and NSC [NOx Storage Catalyst] technology.
“The weight of the vehicle also has a bearing on this, which is why BMW’s lightweighting technologies also have an important part to play,” he added.
A Ford spokesman said: “Our vehicles and engines – including our diesel engines – meet all applicable emissions standards, and they are designed to perform consistently both in the lab and on the road. We do not have any so-called “defeat devices” in our vehicles.
“We fully support efforts to ensure that emission standards closely match the real-world results that customers experience under normal conditions.