Porsche informs authorities of possible new issue with emissions

Volkswagen's Porsche unit said on Thursday it had informed German authorities of potential issues with its emissions data, following a report in Germany's Der Spiegel that the figures for its 911 models of 2016 and 2017 were inaccurate.

"Porsche has identified issues in connection with individual roll-out tests," Porsche said in a statement.

The specific case involves deviations in the measurement of wind resistance values and the corresponding information reported to regulators, the company said. The emissions testing was done in a lab, but a miscalculation in the car's coefficient of drag means it would get lower mileage in the real world.

"The company is continuing its internal investigations in close consultation with the authorities," Porsche said, adding that the problem is not related to engine management software and does not affect vehicle safety.

Under German law, if real-world mileage and emissions vary from an automaker's stated values by more than 10 percent, customers can demand compensation. No word yet on how big the variation is in Porsche's testing.