India to adopt WLTP cycle for BS6 emissions testing from April 2027
India is set to revise how vehicle emissions are measured, with BS6 compliance testing moving to the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) cycle from April 1, 2027. The change will apply to M1 and M2 category vehicles, which include passenger cars as well as commercial passenger buses and vans with a gross vehicle weight of up to five tonnes. The update has been notified through an amendment to the Central Motor Vehicles Rules, 1989, following draft norms issued by the Ministry of Road Transport and Highways in April 2025.
Under the revised framework, all new vehicle models manufactured on or after April 1, 2027, will need to undergo emission testing using the WLTP cycle. These tests will be conducted on a chassis dynamometer, in line with procedures outlined in AIS-175, as amended from time to time. Importantly, while the test method will change, the existing BS6 emission limits will remain unchanged, ensuring continuity in regulatory targets while updating the testing approach.
Currently, India uses the Modified Indian Driving Cycle (MIDC) to measure both fuel efficiency and emissions, including for Corporate Average Fuel Efficiency (CAFE) norms. However, MIDC has long been viewed as less representative of real-world driving conditions due to its fixed speed and time profile. WLTP, which was adopted by the European Union in 2018, is designed to better reflect real-world usage, helping narrow the gap between laboratory results and actual on-road emissions of CO₂, nitrogen oxides and particulate matter.
The move also aligns with broader regulatory developments. The Bureau of Energy Efficiency has proposed transitioning CAFE norms to the WLTP cycle from March 31, 2027, alongside the introduction of CAFE 3 standards. As India continues to tighten its emissions framework following the nationwide rollout of BS6 norms in 2020, the shift to WLTP-based testing is expected to improve the accuracy and credibility of emissions data without altering the fundamental limits manufacturers must meet.
