In a note submitted to the Council before a meeting on 7 June, Germany raised an agenda item on the need to rewrite existing legislation.
Germany has been investigating emissions control systems in diesel vehicles in the wake of Volkswagen's admission last year that it used "defeat device" software in 11 million cars that allowed it to give false results in tests for nitrogen oxide emissions.
While no other manufacturer was using a similar system to Volkswagen's, "it became clear that for many vehicle types, real driving emissions are significantly higher than on the dynamometer", the note from the German delegation said.
Manufacturers adapt emissions control systems to driving and environmental conditions in different ways, but primarily based on a temperature window outside of which the emissions reduction is reduced. This is allowed legally if it is done to protect the engine, but there are doubts over whether this is the case for all the vehicles, and legislation is being interpreted in different ways, the note said.
Legislation should therefore state that defeat devices may only be used if they are needed to protect the engine even when using "the best available technology".
The European Commission needs to "continue to analyse the lessons learned in the US from regulations on the distinction between accepted and prohibited defeat devices" and work on supplementary rules on real driving emissions should be "brought to a speedy and comprehensive conclusion", Germany said.
In the meantime, authorities should demand declarations from manufacturers on any engine protection equipment that they use, including its precise function, the software it uses and why it is needed, it said.
European legislation also needs to improve follow-up checks on vehicles on the road, the note said.
Germany announced in December 2015 that car manufacturers in the country would be required to disclose information on their engine software to regulators.