Before its use of illegal "defeat device" software was discovered, many auto industry executives were baffled by Volkswagen's ability to make diesel cars meet U.S. emissions standards.

One of them was former General Motors car czar and outspoken industry figure Bob Lutz.

During his tenure at GM, Lutz was puzzled by the ability of Volkswagen diesel cars to pass strict U.S. emissions tests.

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GM couldn't figure out how Volkswagen's TDI diesel models met emissions standards, Lutz said in a recent interview on radio station WJR-AM, quoted by Forbes.

During the period that he was product czar from 2001 to 2009, Lutz pushed GM to sell more diesel cars in the U.S.

That led engineers to analyze Volkswagen's TDI models, to see how the company managed to meet U.S. emissions standards.

2015 Volkswagen Passat TDI

2015 Volkswagen Passat TDI

But GM personnel couldn't figure out how VW was able to meet the particularly strict standards in California, Lutz said.

Simply building a car to meet the standards would have compromised fuel economy and performance, and increased price to the point where cars would no longer seem economically viable, he added.

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Lutz previously blamed Volkswagen's illegal actions on the management of former chief Ferdinand Piëch, who was ousted in a boardroom coup a few months before the U.S. Environmental Protection Agency announced the discovery of VW's cheating.

Piëch was hellbent on increasing sales of diesels in the U.S.  as a way to meet fuel-economy standards, and created a culture of fear to get employees to achieve that goal, Lutz has said.

Because Piëch used intimidation to get what he wanted, he is culpable for VW's cheating whether he was directly involved in the creation of the "defeat device" software or not, Lutz has argued.

2014 Volkswagen Passat TDI

2014 Volkswagen Passat TDI

After Lutz left the company, GM proceeded with development of some diesel vehicles.

It eventually did launch a diesel version of the Chevrolet Cruze, but "just to prove we could," Lutz said in the WJR-AM interview.

MORE: Diesels Still Needed For Truck Fuel Economy Despite VW Scandal: Advocate

Despite the VW scandal, the company is expected to continue offering a diesel engine option in the redesigned 2016 Cruze as well.

GM also launched diesel versions of its Chevrolet Colorado and GMC Canyon mid-size pickup trucks shortly after news of Volkswagen's cheating broke.


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