Norway’s state-run advertising watchdog has issued guidelines to advertisers that says, ” “We ask that … phrases such as ‘environmentally friendly’, ‘green’, ‘clean’, ‘environmental car’, ‘natural’ or similar descriptions not be used in marketing cars,” Reuters reports (via Terrapass). Even mentioning the word carbon dioxide draws a red flag.

Carmakers such as Toyota, General Motor’s Opel, Mitsubishi, Peugeot Citroen, Saab and Suzuki had all used phrases this year in advertisements that the watchdog judged misleading.

Cars cannot do anything good for the environment except less damage than others, an official at the watchdog said.

Carmakers would risk fines if they failed to drop the words.

Green car claims have been criticized before. In May, a magazine ad campaign for the Lexus RX 400h was banned by the UK’s advertising watchdog.