Centre Proposes BS7 Emission Norms From April 2029, With Phased Rollout Until 2035

The Ministry of Road Transport and Highways (MoRTH) has proposed introducing Bharat Stage VII (BS7) emission standards from April 1, 2029, with a phased rollout covering passenger and commercial vehicles until 2035. The proposed regulations seek to tighten emission compliance requirements and expand pollution monitoring beyond exhaust gases to include brake and tyre particles.

According to three draft notifications, the proposed standards will amend the Central Motor Vehicles Rules, 1989. They introduce additional requirements for real-world emission testing, onboard monitoring systems, electric vehicle battery durability and the environmental performance of vehicles throughout their operating lives.

Unlike the transition from BS4 to BS6, which significantly tightened tailpipe emission limits, BS7 largely retains existing limits for key pollutants in passenger vehicles. Instead, the proposed framework focuses on stricter testing, monitoring and compliance throughout a vehicle’s operating life.

Under the proposed schedule, new passenger vehicles in the M1 category will come under BS7 from April 1, 2029, with additional requirements taking effect in April 2031 and April 2035. Light commercial vehicles in the N1 category will follow in April 2030, with subsequent phases in April 2032 and April 2035. For medium and heavy trucks and buses in the M2, M3, N2 and N3 categories, the corresponding deadlines are April 2031, April 2033 and April 2035.

For passenger cars, the draft retains the existing BS6 nitrogen oxide (NOx) limits of 60 mg/km for petrol engines and 80 mg/km for diesel engines. However, it introduces particle number measurement covering smaller particles, referred to as PN10, which counts particles measuring 10 nanometres and above, compared with the earlier PN23 threshold of 23 nanometres.

Under the proposed rules, passenger vehicles will have to meet a conformity factor of 1.0 for NOx and particle numbers during real-driving emissions tests from April 1, 2030. Under BS6, vehicles were allowed to exceed laboratory emission limits by up to 43% for NOx and 50% for particle numbers during applicable on-road tests to account for measurement uncertainty. The proposed BS7 requirement removes this additional margin.

A significant change is the proposed regulation of particles released through vehicle braking. From April 2031, conventional internal combustion engine vehicles, hybrids and fuel-cell vehicles in the passenger car category will have a brake particulate matter (PM10) limit of 7 mg/km, compared with 3 mg/km for pure electric vehicles. From April 2035, the limit will be standardised at 3 mg/km across powertrain technologies. Limits for brake particle numbers and tyre abrasion will be notified separately.

The draft also introduces minimum battery durability requirements for electric passenger vehicles and plug-in hybrids. Batteries must retain at least 75% of their original usable energy capacity for up to five years or 100,000 km, whichever comes first. The minimum requirement falls to 67% beyond that period, up to eight years or 160,000 km, whichever comes first.

For commercial vehicles, the proposed framework also covers pollutants such as ammonia, methane and nitrous oxide, alongside conventional exhaust emissions. However, some technical limits relating to brake particles, tyre abrasion and battery durability for heavy vehicles are yet to be specified.

The draft also provides for onboard monitoring systems capable of detecting excessive emissions during vehicle operation. Vehicles will be required to record fuel or energy consumption data, with provisions for sharing certain information over the air in later phases. Another requirement is an Environmental Vehicle Passport, which will provide information on emissions, energy consumption and battery health, where applicable.

India’s Transition From BS4 to BS6

India introduced BS4 emission standards nationwide in April 2017 before moving directly to BS6 in April 2020, skipping the intermediate BS5 stage. The decision to accelerate the transition was taken in January 2016, advancing the BS6 implementation deadline to April 2020 from April 2021, as proposed in an earlier draft notification. The original Auto Fuel Policy had recommended implementation by April 2024.

The transition required substantial changes to engines, exhaust after-treatment systems and fuel quality. Sulphur content in petrol and diesel was reduced from 50 parts per million under BS4 to 10 parts per million under BS6, enabling more effective emission-control technologies.

The BS6 framework was strengthened in April 2023 with mandatory real-driving emission conformity requirements, commonly referred to as BS6 Phase 2. These followed real-world emission measurements conducted for data collection from April 2020. Further onboard diagnostic requirements came into effect in April 2025.

The ministry has invited objections and suggestions from stakeholders within 30 days of the notifications being made available to the public. The regulations remain at the draft stage, and their provisions could change before final notification.