Govt's new move to make official vehicle data mirror real-world performance

The shift means cars will be tested under tougher, more real-world driving conditions before they are approved for sale. As a result, petrol and diesel vehicle standards will be more aligned with those of other global markets, while some experts believe this can also initially increase compliance costs.

The ministry of road transport and highways notified the introduction of Worldwide Harmonized Light Duty Test Procedure (WLTP) for BS6 norms from April 2027, on Wednesday, which will mark the transition from the Modified Indian Driving Cycle (MIDC) for automakers in the country. This aligns India with the European standards of testing vehicles for pollutants.

Simply put, WLTP and MIDC are testing standards that measure a vehicle's fuel efficiency, pollutants, and emissions before it is allowed to be sold in the country. For electric vehicles, the standards help measure the vehicle's range in real-world conditions.

Amit Bhatt, India managing director at the International Council on Clean Transportation (ICCT), said that the introduction of the WLTP standard is an attempt by the government to ensure that compliance with emission and pollutant standards reflects real-world conditions.

While the government has currently notified the change in the measurement of pollutants under BS6 norms, it could soon be followed by the measurement of fuel efficiency and emissions under the same standards under the corporate average fuel efficiency (CAFE) norms.

Compliance measures

Introduced in April 2020, BS6 norms set strict limits on pollutants such as nitrogen oxides (NOx) and particulate matter from petrol and diesel vehicles, which all automakers must comply with. While BS norms limit pollutants, CAFE norms limit carbon dioxide (CO2) emissions by cars in the country. The change in CAFE standards has not yet been announced.

“The shift to WLTP and real-world driving emission testing under the latest BS VI amendment is not about tightening emission limits, but about ensuring compliance reflects more closely how vehicles actually perform on Indian roads,” Bhatt said.

By aligning India’s certification framework with globally harmonised WLTP and real-driving test protocols, the amendment also brings Indian vehicle standards in line with international benchmarks, while making emission testing more rigorous, comprehensive, and reflective of real-world driving conditions, Bhatt added.

Currently, they follow MIDC test standards, which are older than WLTP. The major difference is that the tests under MIDC are shorter and conducted at lower average speeds than those with gentle acceleration.

On the other hand, WLTP tests are longer, testing vehicles at higher speeds and under different driving conditions. As a result, fuel efficiency is lower and total carbon dioxide emissions are higher under WLTP than under MIDC, as they better mirror real-world conditions.

However, higher transparency comes with a price tag. "Any switchover from one system to another imposes costs on manufacturers, which will eventually end up as consumer prices," said Gurudas Nulkar, professor and director, Central for Sustainable Development, Gokhale Institute of Politics and Economics.

Nulkar also noted that the new emissions test is aimed at preventing undetected emission faults. "While the switch to WLTP can be debated by carmakers, the RDE (real driving emission) closes the gap between laboratory results and on-road emissions, by conformity factors," he said. The notification mandates that diagnostic systems be active and effective to prevent undetected emission faults and prioritises social value over private profit through fleet emission management.

Strengthening safety

For a vehicle to be sold in the country, the model must be certified by government-run agencies such as the Automotive Research Association of India (Arai) and the International Centre for Automotive Technology (Icat). These agencies conduct tests to measure pollutants in accordance with BS6 norms and CAFE emission standards.

“MIDC is a relatively gentle cycle with lower acceleration rates and longer idling, resulting in optimistic fuel economy figures, which do not closely resemble real-world conditions. On the other hand, WLTP covers a wider range of speeds and includes more aggressive acceleration and braking events than MIDC,” analysts at Kotak Institutional Equities wrote in an 8 January note.

“As a result, the same vehicle will record higher CO2 emissions on WLTP compared to MIDC.”

Once the measurement of fuel efficiency, emissions and range also shifts to WLTP, it will have implications for both consumers and automakers.

Often, consumers complain that the advertised range figures for EVs and mileage figures for ICE vehicles do not match real-world conditions. Moreover, experts note that emission figures under older testing standards do not accurately reflect vehicle performance in real-world conditions.

While data in the Indian context is limited, a January 2024 ICCT study on the transition of Europe from the older testing cycle to WLTP in 2018 found that the gap between real-world values drastically reduced when WLTP was introduced.

According to the study, carbon dioxide emissions diverged by just 7% in 2018 from recorded real-world values, compared with 33% in the older cycle.

The government's push to obtain more accurate and realistic figures on pollutants comes as it prepares to notify the third iteration of the corporate average fuel efficiency norms, which set a maximum emission target for automakers.