An on-road driving test, using portable emissions measuring equipment, complements Green NCAP’s laboratory tests. The test extends the legislative requirements to get an accurate assessment of real-world emissions.

In addition to the tests carried out in the laboratory, Green NCAP also conducts a real-world driving test, during which tailpipe emissions are collected and sampled. The basis of this test is the Real Driving Emissions (RDE) assessment, introduced into legislation in 2018 to try to control and reduce the gap between emissions values measured in the lab and those emitted in the real world. Green NCAP expands the RDE to make it more challenging and to test under less frequently occurring but realistic traffic situations. Green NCAP’s vision is that an engine shall be clean and energy efficient in every operation point under the torque curve. Examples of these enhanced boundary conditions of the PEMS+ test compared to the regulatory RDE test are 0 – 1300 m altitude vs 0 -700m or an ambient temperature between -7 to 35°C instead of 0 to 30 °C.

Green NCAP road tests

Green NCAP expands the current legislative Real Driving Emissions assessment to make it more realistic.

The drive is split into three parts, representing urban, rural and motorway driving, and exhaust gases are collected from the tailpipe by a Portable Emissions Measurement System (PEMS), attached to the back of the car. The pollutant emissions measured are NOx, CO and PN. In the future, more robust measurement of hydrocarbons using PEMS will allow the inclusion of this pollutant in the calculation of the Clean Air Index.

The PEMS testing consists of a variety of real-world scenarios from fuel saving eco-friendly driving to more dynamic, heavy load driving:

  • PEMS+ regular (normal real world driving with cold engine start)
  • PEMS+ eco light (fuel saving eco-friendly real world driving with warm engine start)
  • PEMS+ heavy load (Dynamic heavy load sporty driving with warm engine start)
  • PEMS+ Congestion simulation (Long idling, stop and go to simulate heavy congestion)
  • PEMS+ regular first 8 km (Simulating short urban trip with cold engine start).

With the exception of the congestion test, plug-in hybrid electric vehicles (PHEVs) are subjected to all of these road tests, both in charge-sustaining mode (i.e. when running mainly using the combustion engine) and in charge-depleting mode (i.e. when being run primarily on battery power).