The EC believes that Germany has not complied with the EU directive because of allowing Daimler to sell its cars within the EU which don't comply with the so-called 'MAC directive' on refrigerants.
Daimler refused to use alternative, low GWP refrigerants in its cars, because it was worried about their safety implications. The company continied to use R134a in its cars, which is banned for new cars. Daimler refused to use R1234yf. From 1st January 2017, all refrigerants with a GWP higher than 150 will be banned in new cars.
Daimler was the only car manufacturer worried about using the new refrigerants. Germany's motor industry trade body, the Federal Motor Transport Authority, and Joint Research Centre of the European Commission were not concerned either, having carried out risk analysis in 2014.
The German government, however, took no action against Daimler for continuing to use R134a, which is why the EC has now refereed the case to the court.