The future Euro 6d regulation contains since 2017 Real Driving Emissions (RDE) as an mandatory test type. With RDE legislation, the road is becoming a new test environment for exhaust emissions and certification of vehicles. Compared to current test environments that have been designed and optimised to achieve perfect reproducibility and exclude external influences, road driving under real conditions will never be 100% reproducible.

However reproducible tests are of major importance in the development phase, RDE cycles are increasingly being mirrored from the public road to the vehicle's chassis roller and the engine test bench calling "road to rig".