Deteriorating air quality is a major health concern for most of the Indian cities, and one of the major reasons for this is vehicular emissions. Despite tightening of norms in the automotive sector, by mandating Bharat Stage-VI (BS-VI) standards for tailpipe emission and fuel efficiency standards, as well as the Corporate Average Fuel Economy (CAFE) regulations for passenger vehicles, there is no visible improvement in air quality.

Apart from rising number of vehicles on the roads, the presence of old and inefficient vehicles is a significant reason for poor air quality.

There has been limited success in phasing out old polluting vehicles. As ownership changes hands, vehicles move from cities to peri-urban areas and finally to rural areas.

Real-world numbers

Studies reveal that emissions during actual driving conditions exceed laboratory-tested figures, often by substantial margins. This underscores a critical gap between regulatory standards and environmental impact. In some developed as well as developing countries, efforts are on to achieve real-world emission numbers before rolling out internal combustion engine (ICE) vehicles.

For instance, the US Environmental Protection Agency (EPA) has a mandate to randomly pick up privately-owned vehicles and test them at the National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Michigan. Every year, about 150 such vehicles from across the country are tested under the agency’s surveillance programme. Any discrepancy witnessed during the check is taken up with the respective manufacturers and detailed investigation ensues.

In India, the regulatory authorities are making efforts to shift from Modified Indian Driving Cycle (MIDC), equivalent to the New European Driving Cycle designed in 1980s, to the Worldwide-Harmonised Light Vehicle Test Procedure (WLTP) while testing ICE vehicles in the laboratories for compliance. The move towards WLTP, already adopted under European Union law, is a welcome and commendable step; however it is almost impossible to replicate real world driving cycles under different geographical and climatic conditions.

Besides stringent fuel economy and emission norms, the actual on-road performance of the vehicles is dependent on the driving behaviour, and road and traffic conditions. The recent draft proposal of Bureau of Energy Efficiency for CAFE-III and CAFE-IV norms for M1 category — that is, passenger vehicles weighing less than 3.5 tonnes — as well as the shifting to BS-VII regime, will be a game changer in the automotive sector.

While passenger cars and heavy-duty vehicles are regulated for green-house gas emissions, smaller vehicles like two-wheelers and light/medium-duty vehicles, which account for much of new ICE vehicle sales, also need comparable regulatory control.

The Pollution Under Control certification, predominantly reliant on idle mode testing, fails to capture emissions during real driving scenarios. This outdated approach undermines efforts to mitigate vehicular pollution effectively.

Efficiency improvements are pivotal in the battle against transport emissions. By promoting technologyand incentivising cleaner ICE vehicle designs, governments can foster a shift towards more sustainable transportation solutions. However, bridging the gap between emissions standards and real-world performance remains a formidable challenge, necessitating robust testing methodologies aligned with actual driving conditions.

Achieving meaningful emission reductions demands collaborative efforts from automotive manufacturers, regulatory bodies, and civil society. Manufacturers must prioritise innovation in emission control technologies, while regulators must enforce stringent compliance measures.

Rao is Distinguished Fellow, and Qamar is Associate Director, The Energy and Resources Institute