Real Driving Emissions (RDE)

Real Driving Emissions (RDE) is an on-road vehicle emissions testing procedure introduced in the European Union to measure pollutant emissions under actual driving conditions. Using Portable Emissions Measurement Systems (PEMS), vehicles are tested on public roads across urban, rural, and motorway routes to verify compliance with legal emissions limits, particularly for nitrogen oxides (NOx) and particulate emissions. RDE complements the laboratory-based WLTP procedure by helping regulators ensure that vehicles meet emissions standards during real-world operation rather than only in controlled laboratory environments.