The 911 Turbo S model of Porsche dazzles at Detroit's North American Auto this year in the United States. [Photo/Xinhua]

German regulators are investigating whether Porsche illegally manipulated fuel-economy data on its vehicles, potentially opening a new front in parent Volkswagen AG's emissions-cheating scandal.

Germany's Transport Ministry and Federal Motor Transport Authority are examining whether Porsche installed devices allowing its cars to sense whether they were being tested for fuel consumption and carbon-dioxide emissions, representatives at both agencies said on Thursday.

That type of technology can be used to falsify results by making cars appear more energy efficient during tests.

Porsche rejected allegations that its cars manipulate test results, a spokesman said by phone, adding that the Stuttgart, Germany-based maker of the 911 sports car is cooperating fully with the authorities on the investigation.

Volkswagen has so far set aside 18.2 billion euros ($19.7 billion) for fines and related expenses after acknowledging last year that it rigged 11 million diesel vehicles to cheat on emissions tests.

The revelations have increased scrutiny of auto emissions with regulators around the world stepping up investigations. German magazine WirtschaftsWoche reported earlier that unidentified people close to Porsche tipped of the Transportation Ministry to the alleged cheating. According to the report, some Porsche cars can detect whether they're on a test bed based on the lack of steering wheel movement during operation. German authorities started a similar investigation targeting Audi in November, the magazine said.

Porsche said technology that allows its cars to sense steering movements are used to improve the car's performance when driving and are not related to emissions testing.

The shares of Volkswagen have lost almost 20 percent since the scandal broke in September 2015, reducing the company's valuation to 67 billion euros.

Bloomberg