Worldwide Harmonised Light Vehicles Test Procedure

One of the main goals of the WLTP is to better match the laboratory estimates of fuel consumption and emissions with the measures of an on-road driving condition.

[4] Since CO2 targets are becoming more and more important for the economic performance of vehicle manufacturers all over the world, WLTP also aims to harmonize test procedures on an international level, and set up an equal playing field in the global market.

[7] From 1 September 2019 all light duty vehicles that are to be registered in EU countries (and also in Switzerland, Norway, Iceland and Turkey) must comply with the WLTP standards.

[4] The WLTP replaces the old NEDC as the European homologation lab-bench procedure, which was established in the 1980s to simulate urban driving conditions for a passenger car.

[8] In 1992 the NEDC was updated to also include a non-urban path (characterized by medium to high speeds), and finally in 1997 CO2 emission figures were added, too.

[9] Nowadays, the NEDC cycle has become outdated since it is not representative of modern driving styles, as the distances and road varieties a mean car has to face have changed since the test's design.

In each class, there are several driving tests designed to represent real world vehicle operation on urban and extra-urban roads, motorways, and freeways.

[citation needed] To ensure comparability for all vehicles, thus guaranteeing a fair comparison between different car manufacturers, the WLTP tests are performed in the laboratory under clear and repeatable conditions.

In fact, these points depend on vehicle unique parameters as weight, torque map, specific power and engine speed.

From that date, measures of fuel consumption and CO2 emissions obtained under WLTP are the only ones with legal validity and are to be inserted in official documentations (the Certificate of Conformity).

[5] A vehicle’s performance does not change from one test from the other, simply the WLTP simulates a different, more dynamic path, reflecting in a higher mean value of pollutants.

[15] Along with the lab-based procedure, the UNECE introduced a test in real driving conditions for NOx and other particulate emissions, which are a major cause of air pollution.

[4] In addition, the freestream air that the vehicle receives is not conditioned by the wind blower position, which could cause alterations in the measured emissions of laboratory tests.