India To Adopt WLTP Cycle For BS6 Emissions Testing From April 2027: Key Details

India is set to change how BS6 emission testing works from April 1, 2027, and it will affect every new car that goes through certification. The government will move to the Worldwide Harmonised Light Vehicle Test Procedure, or WLTP, replacing the Modified Indian Driving Cycle used so far. The new test cycle will apply to passenger cars and light commercial passenger vehicles under five tonnes. For anyone who keeps an eye on official mileage figures and spec sheets, this shift matters because the numbers printed for fuel efficiency and emissions will come from a different test method. Carmakers will need to retune engines, update software and run fresh certification tests, so the move will shape future launches, facelifts and even models that continue on sale into the next cycle.

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WLTP will now be used to measure tailpipe emissions and fuel consumption during type approval at certified test facilities. The tests will still run on chassis dynamometers, but the drive pattern will change. Brands will have to submit WLTP-based data for all new vehicles introduced after the deadline and for current models that stay in production. That means development teams will begin recalibration work well in advance, especially for turbo petrol, diesel and hybrid powertrains that rely on precise tuning to meet emission limits.

This shift also brings India closer to global testing practices already used in Europe and other regions. WLTP follows a longer and more varied speed pattern that aims to reflect real driving conditions more closely than the current cycle. As a result, official fuel efficiency figures could change once the new test becomes standard. Anyone comparing mileage across different models in the future will be looking at WLTP-based numbers instead of the older test results.

The rule will cover hatchbacks, sedans, SUVs, MPVs and vans within the weight limit, along with certain passenger-focused commercial vehicles. Carmakers will need to align testing schedules, update certification documents and make sure engines meet the revised cycle. Some models could see changes to claimed mileage figures once they transition to WLTP certification, even if the mechanical package stays the same.

The move will also tie into Corporate Average Fuel Efficiency norms, since WLTP data will be used for compliance calculations. India introduced BS6 emission standards in 2020, and this 2027 update does not bring a new emission stage. Instead, it changes the test method within the same BS6 framework. Carmakers are expected to prepare their portfolios for the switch as the April 2027 deadline approaches, with new and continuing models moving to the updated testing cycle.