Draft BS-VII Norms: Real-World Emissions Testing and Brake-Tyre Pollution Controls

What the draft changes: Broader regulation, not merely tighter exhaust limits

The proposed BS-VII framework covers exhaust emissions, smaller particles, real-world performance, non-exhaust pollution and battery performance. Its implementation is staggered by vehicle category and by individual requirement, so the initial rollout date does not activate every provision simultaneously.

For passenger cars, the principal limits for carbon monoxide, nitrogen oxides and exhaust particulate matter are retained. The particle-number measurement threshold would fall from 23 nanometres to 10 nanometres, bringing smaller particles within the measurement regime.

• Passenger cars would enter the proposed regime from 1 April 2029, followed by light commercial vehicles in April 2030 and buses and heavy trucks in April 2031.
• Petrol-car limits would be 1,000 mg/km for carbon monoxide and 60 mg/km for nitrogen oxides.
• Diesel-car limits would be 500 mg/km for carbon monoxide and 80 mg/km for nitrogen oxides.
• The proposed exhaust particulate-matter limit would be 4.5 mg/km for both petrol and diesel cars.
• The draft specifies performance requirements rather than prescribing a particular engine design.

Real-world testing and monitoring: Closing the compliance gap

The draft proposes on-road testing with portable equipment as part of passenger-car type approval from April 2030. This should be understood as strengthening the existing real-driving emissions framework, not introducing on-road emissions testing in India for the first time.

Laboratory testing provides controlled, repeatable measurements, but actual emissions can vary with traffic, driving patterns, load and environmental conditions. Combining laboratory tests, on-road measurement and monitoring over time can make certification more representative of vehicle use.

For cars, an on-board monitoring system would detect specified emissions exceedances, including levels at least 2.5 times the relevant limit. Monitoring data would have to be accessible through the diagnostic port for vehicles manufactured from 1 April 2032; the draft also phases in monitoring of emissions and fuel or electric-energy consumption.

• Certification should establish initial compliance, while monitoring and durability checks should help verify continued performance.
• Monitoring data can support enforcement only when diagnostic access, verification protocols and corrective-action procedures are effective.

Brake and tyre pollution: Why electrification alone is insufficient

Brakes release particles as friction surfaces wear, while tyres shed material through contact with the road. These sources remain relevant even when tailpipe emissions are eliminated, making non-exhaust controls important for both conventional and electric vehicles.

For passenger cars, the draft proposes brake-particle limits of 3 mg/km for pure electric cars and 7 mg/km for other specified vehicle types from April 2031. A common limit of 3 mg/km across powertrains is proposed from April 2035.

Passenger-car tyre-abrasion requirements are proposed from April 2031, but their numerical limits would be notified separately. Electric vehicles and plug-in hybrids would also face battery-performance benchmarks; these address performance retention over time and should not be confused with particulate-emission limits.

• Regenerative braking can reduce reliance on friction brakes, but it does not eliminate tyre wear.
• Regulating wear particles complements electrification rather than replacing its benefits.
• Particle-number measurement, particulate mass and tyre abrasion are distinct regulatory parameters.

Category-specific obligations and the regulatory framework

Light commercial vehicles would face weight-dependent requirements from April 2030. Their brake-particle requirements would begin in April 2032, with a common limit across powertrains proposed from 2035; numerical brake limits would be notified separately.

Buses and heavy trucks are covered by a separate draft. Their exhaust limits are expressed relative to engine energy output rather than distance travelled, reflecting their different duty cycles. The draft covers nitrogen oxides and particles as well as ammonia, methane and nitrous oxide, with the longest proposed durability period extending to 875,000 km or 15 years.

The legal context includes the Motor Vehicles Act and the Central Motor Vehicles Rules. Articles 48A and 51A(g) provide broader constitutional environmental context, but the specific compliance duties must come from the applicable vehicle rules. Publication of a draft does not make its proposed limits final or immediately enforceable.

• Heavy-vehicle exhaust limits, on-road testing and on-board monitoring are proposed from April 2031.
• Additional heavy-vehicle monitoring and brake-particle requirements are proposed from April 2033.
• Heavy-vehicle tyre-abrasion requirements are proposed from April 2035; numerical brake, tyre-wear and battery-performance limits would be notified separately.

Implementation economics: Standards must be matched by enforcement capacity

Manufacturers may need additional testing, sensors, calibration, exhaust-treatment improvements or software changes, depending on existing vehicle technology. Brake and tyre compliance and battery-performance verification could add further development costs; however, a uniform cost increase across models cannot be inferred from the supplied material.

The public-health value of stronger standards depends on credible measurement and sustained compliance. Portable testing equipment, calibrated instruments, trained personnel and reliable data systems are therefore as important as the notification itself.

Phasing provides preparation time, but unresolved numerical limits can delay product planning and testing investment. The central policy task is to combine predictable requirements with technically robust enforcement, without treating certification alone as proof of lifetime compliance.

• Cost impacts may differ across vehicle categories, technologies and manufacturers.
• New-vehicle standards should be complemented by maintenance and in-use compliance measures for the existing fleet.
• Independent verification and transparent testing procedures can strengthen confidence in manufacturer-reported compliance.