BS6 emissions testing to adopt WLTP cycle from April 2027

Effective from April 1, 2027, emission standards for BS6 vehicles – M1 and M2 categories – will be tested using the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) cycle. Category M1 and M2 vehicles include passenger cars and commercial passenger buses and vans with a gross weight of under 5 tonnes. The changes were notified via an amendment to the Central Motor Vehicles Rules, 1989, following draft norms issued by the Ministry of Road Transport and Highways on April 28, 2025.

1. Change to apply to passenger cars and commercial buses and vans
2. CAFE norms also currently use the MIDC cycle
3. European Union adopted the WLTP cycle in 2018
4. WLTP emission tests will be conducted on a chassis dynamometer

Move to WLTP will better reflect real-world emissions

The WLTP cycle is seen as a closer match to real-world driving than older lab-based test cycles. In India, both fuel efficiency and emissions are currently tested using the Modified Indian Driving Cycle (MIDC), a fixed speed-distance-time map. WLTP, adopted by the European Union in 2018, narrows the gap between laboratory results and on-road emissions of CO₂, nitrogen oxides and particulate matter.

As per the notification, WLTP-based emission standards will apply to all new vehicle models manufactured on or after April 1, 2027. Emission testing under WLTP will be carried out on a chassis dynamometer, in line with procedures specified in AIS-175, as amended from time to time.

India rolled out BS 6 emission norms nationwide in April 2020, significantly tightening emission standards. The shift to WLTP-based testing is expected to make emissions data more representative of real-world driving while keeping the existing BS 6 limits unchanged. CAFE norms also currently use the MIDC cycle. However, the Bureau of Energy Efficiency has proposed a move to WLTP from March 31, 2027, alongside the introduction of CAFE 3.

With inputs from Uday Singh.