German carmakers have promised to swiftly investigate experiments that exposed people and monkeys to diesel fumes, disclosures that threaten to open a new phase in an emissions controversy that has dogged the industry since 2015.
"The boundaries of decent and moral conduct were clearly crossed", said Bernd Osterloh, VW's labour boss, adding he will leave no doubt about workers' opposition to such tests at next week's meeting.
It reported they were given varying doses over a period of hours at an institute belonging to Aachen University in 2012, with a summary of the report showing no ill effects. The new scandal has sent shockwaves through Germany and the country's environment minister described the experiments as "abominable".
"We are convinced that the scientific methods chosen at the time were wrong".
Daimler AG said it was "appalled by the nature and extent of the studies".
The New York Times reported on Friday that research aimed at defending the fuel's impact on the environment was carried out at a lab in the United States in 2014.
The Beetle being used was equipped with VW's now notorious emissions testing recognition software, which recognised when a vehicle was being subjected to a laboratory or open-road test cycle, cutting engine performance and emissions dramatically.
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Marketing professor Alan Middleton at York University's Schulich School of Business agrees with that assessment, saying the scheme was likely one of the automaker's attempts to promote diesel as a cleaner fuel alternative.
Vehicle industry-sponsored research "all has the same fundamental aim", Joachim Heinrich, an environmental health expert at the University of Munich, tells The New York Times.
The German establishment as a whole widely condemns the tests.
Despite the wave of apologizes, the monkey business isn't going away anytime soon as Reuters reports Volkswagen's supervisory board has called for an investigation into who commissioned the tests. Reports of the human tests followed a New York Times account of similar experiments on monkeys in the USA, prompting automakers to distance themselves from the work.
It remains unclear whether the carmakers were aware of monkeys being used in the experiments.
VW said on Monday the EUGT study was never discussed in any management board meetings, after the Bild newspaper reported an internal e-mail showed at least some senior managers were informed about the design of the research.
VW and the other automakers are now facing a public backlash for the LRRI tests as cruelty against animals.
"In the name of the entire supervisory board, I would emphatically distance myself from such practices [.] The events that took place have to be unreservedly and comprehensively cleared up", said Volkswagen supervisory board Chairman Hans Dieter Poetsch in a statement.
BMW told the press that it had not participated in the studies cited in media and had launched an "immediate internal investigation" into the work of EUGT.