WLTP test hugely over-estimates fuel economy, says study

The Worldwide Harmonised Light Vehicle Test Procedure (WLTP) arrived in 2017, replacing the New European Driving Cycle (NEDC) test.

According to the European Court of Auditors & the European Commission, the real-world data on the fuel economy of petrol, diesel and plug-in hybrid cars are hugely different from their official laboratory-calculated fuel consumption & CO2 emission figures.

As per the report, when the first sample of cars registered in 2022 was tested, the WLTP test regime overestimated the fuel economy of petrol cars by 23.7% and diesel cars by 18.1%. Similarly, PHEVs averaged CO2 emission figures of 139.5 g/km - which was 23% better than the average of ICE engines. However, in the real world, the report suggested that PHEVs aren't being charged as often as estimated in the WLTP tests.

The Worldwide Harmonised Light Vehicle Test Procedure (WLTP) arrived in 2017, replacing the New European Driving Cycle (NEDC) test, which dates back to 1992. The WLTP tests are longer, conducted over a larger distance, less stopping, higher average speeds and require greater levels of acceleration.

The WLTP test regime was assured to be "based on a global statistical survey of real driving profiles". However, since 2021, the EU has found the tests to be significantly overestimating the real-world economy of vehicles.

The EU got proof of this after installing onboard fuel consumption monitoring devices in each vehicle sold in its member countries. The first results of these monitoring devices have now come out, throwing doubt on the official test figures.

The European Court of Auditors stated, "The key challenge for meeting emission-reduction targets for 2030 and beyond will be to ensure a sufficient uptake of zero-emission vehicles. In particular, it will be important to address electric vehicle affordability, provide sufficient electric vehicle charging infrastructure and secure the supply of raw materials to produce batteries."

It further stated, "The Commission should assess the feasibility, costs and benefits of the following changes to the [current] CO2 regulation, replacing the current EU and manufacturer-level targets with targets based instead on a minimum share of zero-emission vehicles."

Source: Autocar UK