As India strengthens its efforts towards formulating Bharat Stage VII (BS VII) emission norms, it is looking at the tightening of tailpipe limits, with a target of making a transformative leap in reducing vehicular emissions that are a big challenge for the country.
Delivering a comprehensive technical presentation at the ECMA Roundtable in New Delhi, Dr Ameya Joshi, Founder, MobilityNotes and former Director of Emerging Technologies, Regulations and Electrification, at Corning, laid out a compelling roadmap for what BS VII should look like – drawing on international benchmarks while keeping Indian conditions front and centre.
“India must build on BS VI not just by adding layers, but by rethinking the emissions framework to suit its unique mobility landscape, climate, and vehicle parc,” Dr Joshi stated.
While Europe has shown a degree of reluctance to make large sweeps in the final stretch of ICE vehicle regulations due to a more rigorous EV transition timeline, India cannot afford to copy-paste those measures.
For India, the message is clear: don’t wait. Dr Joshi emphasised that particulate number (PN) limits must be expanded to include all vehicle types, not just gasoline direct-injection or diesel engines. Studies have shown that even port fuel-injected vehicles emit similar levels of ultrafine particles, yet they escape regulatory scrutiny.
“Technology exists to remove over 95% of particulate matter (PM) emissions, even those smaller than 23 nanometres. So why delay applying the standard to all vehicles?” Joshi questioned.
He backed this with data showing that 20 million two-wheelers – the predominant mobility mode in India – emit more PM per kilometre than four-wheelers, especially during cold starts. And modern, cost-effective filters can eliminate these emissions.
India-specific solutions
While European temperature limits for testing evaporative emissions are capped at 35°C, this is grossly inadequate for Indian cities where temperatures regularly exceed 40-45-degree Celsius for several months.
“Temperature has a nonlinear impact on evaporation,” Dr Joshi explained. “So, a 5-degree Celsius difference can dramatically increase evaporative losses. That’s why India needs to set evaporative test conditions at at least 40-degree Celsius, and account for fuels with higher ethanol blends like E20.”
“Brazil has already taken this step, and their climate is closer to ours,” he added.
He presented real-world test results showing that evaporative emissions increased by 2.5 times when tested at 45-degree Celsius with E20 fuels compared to standard European conditions with E0.
Curbing evaporative emissions
The regulatory focus on tailpipes has obscured an equally damaging source: evaporative emissions from parked vehicles, fueling events, and heat-induced fuel vaporisation.
Using a combination of actual test data and simulation, Dr Joshi showed that diurnal and refueling emissions can often surpass tailpipe hydrocarbon emissions.
“A parked vehicle on a hot day in Delhi without a properly sized carbon canister can emit over 10x more hydrocarbons than it does from the tailpipe during an average 33km drive,” he said.
The solution, as per Dr Joshu, lies in mandating onboard refueling vapor recovery (ORVR) systems, long used in the U.S, as well as increasing the canister size from the Euro 6D norm of 1.2 litres to about 2.1 litres to account for India’s higher volatility and heat.
While the BS VI emission norms introduced portions of real driving emissions (RDE), Dr Joshi emphasised the need to widen the net to include all vehicles, all test conditions, and focus on low temperatures, relevant for several North Indian cities.
“Particle formation increases drastically below 10-degree Celsius. Some Indian cities drop below 5°C for significant parts of the year. We must test accordingly,” he pointed out.
He made a recommendation to lower the temperature boundary for RDE testing to 5-degree Celsius, and ensure that sub-23 nanometre particles are measured and regulated, as these ultrafine particles are the most harmful and most prevalent during cold starts and high accelerations.
While industry often raises the spectre of costs, Dr Joshi made a strong case that most of these technologies – filters, ORVR systems, larger canisters – are well proven, not expensive, and in some cases, actually save fuel.
“These systems are not just cost-effective. They recover fuel that would otherwise be lost as vapor. That’s both environmental and economic efficiency,” he said.
Dr Joshi also cited modeling that showed cost recovery within a few years, especially as fuel prices remain high and consumers value operating cost savings.
Hydrogen for heavy vehicles
In a brief but insightful segment on heavy-duty vehicles, Dr Joshi pointed out that new engine designs, dual SCR systems, and even hydrogen combustion are gathering momentum. While hydrogen trucks may require 6kg of hydrogen to run 100km, manufacturers are rapidly improving engine thermal efficiency, exploring direct hydrogen injection, and simplifying after-treatment systems using hydrogen oxidation catalysts.
India’s push for green hydrogen could accelerate this trend, especially in high-utilisation, long-haul segments where battery-electric vehicles face limitations.
While Europe is preparing for a gradual decline in ICE vehicles, India is likely to be the last country standing in the application of the internal combustion engine with its vast geography and large pool of vehicles across all categories.
Dr Joshi’s focal argument was that BS VII must not be a symbolic update. It must be a science-driven, health-centered, climate-resilient framework, taking the best of global best practices while tailoring them rigorously for Indian realities. “Our journey is different, and our citizens deserve cleaner air, regardless of propulsion technologies,” he concluded.