Real-world fuel economy measurements: technical insights from 400 tests of Peugeot, Citroen and DS cars

The intention was to provide customers with robust information about fuel economy that was representative of the typical driver for each model selected. The frst results were published in 2016 and by the end of 2017 the aim was for the whole fleet to be covered, including pollutant measurements. In order to ensure robust, repeatable and representative measurements, a testing ‘Protocol’ was developed. This procedure has now been used to conduct more than 400 tests on more than 60 PSA vehicles and over 1,000 model variants.

This report provides a meta-analysis of the results and provides valuable insights on real-world driving emissions, differences compared to laboratory test procedures and the real effectiveness of different technologies on the road.

Overall, the results clearly show PEMS tests for CO₂ fuel economy provide a robust, representative and sufficiently repeatable basis for measuring the real-world fuel economy and CO₂ emissions of vehicles. However, the measurement device does need to improve its reliability (8% of the tests failing for instrument reasons), especially the accuracy of the exhaust mass flow measurement for gasoline engines, particularly in challenging low mass flow environments such as urban environments.