As Delhi Chokes Under Toxic Air, Can Plug-In Hybrid Cars Actually Reduce Pollution?

Last Updated:October 22, 2025, 19:57 IST

Are you really reducing pollution with your hybrid? Research shows plug-in hybrids emit nearly as much as petrol cars. Here’s how Delhi’s AQI and your vehicle habits connect

In India over the last five years, the purchase of hybrid cars has increased significantly, with some reports showing more than a doubling of sales in the first half of this year compared to the previous years.

Delhi’s air quality continues to deteriorate with every passing day, reaching levels that pose severe health risks to its residents. Although festival-related firecrackers are often blamed for sudden spikes, the steady increase in the number of vehicles in the Delhi-NCR region remains a significant contributor.

During the recent Diwali period, leading automobile manufacturers recorded some of their highest sales ever. Industry estimates indicate that passenger-vehicle makers experienced sales growth of between 15% and 35% during the festival season. Maruti Suzuki reported 450,000 bookings during this period, with retail sales reaching a record 325,000 units. Tata Motors delivered over 100,000 vehicles, a 33% increase year-on-year, while Hyundai Motor India saw retail sales surge by 30%, averaging approximately 2,500 cars daily.

In India over the last five years, the purchase of hybrid cars has increased significantly, with some reports showing more than a doubling of sales in the first half of this year compared to the previous years. This surge is driven by a demand for better fuel efficiency, concerns about the limited charging infrastructure for electric vehicles and rising pollution.

Even though plug-in hybrid cars are marketed as a cleaner alternative to petrol vehicles. Yet, despite their growing popularity, recent reports suggest that plug-in hybrid cars may pollute almost as much as petrol vehicles, raising urgent questions about their effectiveness in improving air quality in India’s major cities.

With this surge in vehicles, it is essential to understand how hybrid cars function, their real-world impact on emissions, and whether they offer the environmental benefits advertised.

How Do Vehicles Contribute to Air Pollution?

Transport emissions are among the most significant contributors to air pollution in Delhi-NCR. The region frequently experiences hazardous levels of particulate matter (PM2.5), which can penetrate deep into the lungs and enter the bloodstream. Vehicles contribute over 20% of the city’s emissions, combining exhaust gases such as nitrogen oxides, carbon monoxide, and particulate matter.

According to a 2023 report by the Central Pollution Control Board (CPCB), the Air Quality Index (AQI) in Delhi reached “severe” levels for more than 50 days in the year. Traffic congestion, especially during peak hours, intensifies pollution, while weather conditions such as low wind speeds and temperature inversions trap pollutants close to the ground. Even hybrid and electric vehicles, when relying on combustion engines or charged using electricity from fossil fuel-based grids, still contribute to the city’s overall pollution load.

What Is a Plug-in Hybrid Vehicle?

A plug-in hybrid electric vehicle (PHEV) combines a petrol or diesel engine with an electric motor and a rechargeable battery. Unlike conventional hybrids, which primarily use the electric motor to support the combustion engine, PHEVs can operate on electricity alone for short distances. Fully electric vehicles (EVs), on the other hand, rely exclusively on electric power and produce zero tailpipe emissions.

How Is A Hybrid Car Different from a Petrol Car?

Understanding these differences is essential when considering a purchase. Petrol cars depend entirely on combustion engines, producing continuous emissions. Traditional hybrids reduce emissions through energy-efficient management but still rely on petrol. Plug-in hybrids were marketed as a solution for longer journeys with reduced emissions; however, real-world usage often falls short of laboratory efficiency claims.

Petrol vs Hybrid: Key Differences

Fuel efficiency is the primary advantage of hybrid vehicles. Regenerative braking, electric motor assistance, and the ability to shut off the petrol engine while idling help hybrids achieve significantly higher mileage.

Why Do Plug-in Hybrids Pollute Nearly as Much as Petrol Cars?

Despite expectations, plug-in hybrids often fail to deliver substantial reductions in real-world emissions. A report by the non-profit advocacy group Transport and Environment found that PHEVs emit only 19% less carbon dioxide than traditional petrol and diesel vehicles, far below previous laboratory estimates of 75%.

Researchers analysed data from onboard fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO2 emissions in 2023 were 4.9 times higher than laboratory tests suggested. The discrepancy largely arises from overestimating the “utility factor,” the proportion of miles driven in electric mode. The study found that only 27% of driving occurred in electric mode, compared to an assumed 84%.

Even in electric mode, PHEVs often burn fossil fuels for one-third of the distance because electric motors are insufficient for certain driving conditions. The gap between lab and real-world emissions has political and economic consequences, as carmakers have avoided substantial fines by complying with EU CO2 targets under false efficiency assumptions.

A separate study published in Environmental Research Letters in January 2024 emphasised that electrification is only as effective as the electricity grid. Cities powered by coal-heavy grids see smaller reductions in PM2.5, whereas a renewable-heavy grid maximises the environmental benefits of PHEVs and EVs. In India, Delhi, Mumbai, and Bengaluru would benefit most from cleaner grids, potentially improving public health significantly.

How Does This Really Affect You and Your Family?

Delhi’s residents face immediate health risks from high PM2.5 levels. Short-term exposure can trigger asthma attacks, bronchitis, cardiovascular events, and airway inflammation. While hybrid vehicles emit less pollution than conventional petrol cars under ideal conditions, the difference is modest in real-world urban driving.

Even small contributions from hybrids accumulate when thousands of vehicles operate daily in congested city conditions. Air pollution spikes can cause immediate respiratory and cardiovascular effects, particularly among children, the elderly, and people with pre-existing health conditions. The need to manage emissions from all vehicle types remains urgent to reduce these health risks.

If Hybrids Are Not That Effective, Is There a Better Option?

Fully electric vehicles (EVs) offer zero tailpipe emissions, representing a significant improvement over hybrids. Widespread adoption requires attention to grid emissions, charging infrastructure, and consumer behaviour. Policy measures such as improved public transport, carpooling incentives, and emission-based road taxes can reduce the overall number of polluting vehicles.

Renewable energy adoption for charging EVs ensures that vehicle electrification genuinely reduces urban air pollution. Strategic urban planning, including traffic management, low-emission zones, and expansion of green spaces, can further mitigate pollution exposure. Personal choices, such as reducing vehicle use or shifting to EVs, directly affect both individual and public health outcomes.

What Does This Mean for Car Owners or Residents?

Hybrid vehicles provide environmental benefits under certain conditions, particularly when regularly charged and driven efficiently. However, they are not a panacea for urban air pollution. Residents should consider commuting patterns, city infrastructure, and available vehicle technologies when evaluating options.

For Delhi-NCR residents, mitigating pollution exposure involves a combination of vehicle choice, behavioural adjustments, and support for broader policy initiatives aimed at cleaner energy and transportation solutions.

In India over the last five years, the purchase of hybrid cars has increased significantly, with some reports showing more than a doubling of sales in the first half of this year compared to the previous years. This surge is driven by a demand for better fuel efficiency, concerns about the limited charging infrastructure for electric vehicles and rising pollution.

Even though plug-in hybrid cars are marketed as a cleaner alternative to petrol vehicles. Yet, despite their growing popularity, recent reports suggest that plug-in hybrid cars may pollute almost as much as petrol vehicles, raising urgent questions about their effectiveness in improving air quality in India’s major cities.

With this surge in vehicles, it is essential to understand how hybrid cars function, their real-world impact on emissions, and whether they offer the environmental benefits advertised.

How Do Vehicles Contribute to Air Pollution?

Transport emissions are among the most significant contributors to air pollution in Delhi-NCR. The region frequently experiences hazardous levels of particulate matter (PM2.5), which can penetrate deep into the lungs and enter the bloodstream. Vehicles contribute over 20% of the city’s emissions, combining exhaust gases such as nitrogen oxides, carbon monoxide, and particulate matter.

According to a 2023 report by the Central Pollution Control Board (CPCB), the Air Quality Index (AQI) in Delhi reached “severe” levels for more than 50 days in the year. Traffic congestion, especially during peak hours, intensifies pollution, while weather conditions such as low wind speeds and temperature inversions trap pollutants close to the ground. Even hybrid and electric vehicles, when relying on combustion engines or charged using electricity from fossil fuel-based grids, still contribute to the city’s overall pollution load.

What Is a Plug-in Hybrid Vehicle?

A plug-in hybrid electric vehicle (PHEV) combines a petrol or diesel engine with an electric motor and a rechargeable battery. Unlike conventional hybrids, which primarily use the electric motor to support the combustion engine, PHEVs can operate on electricity alone for short distances. Fully electric vehicles (EVs), on the other hand, rely exclusively on electric power and produce zero tailpipe emissions.

How Is A Hybrid Car Different from a Petrol Car?

Understanding these differences is essential when considering a purchase. Petrol cars depend entirely on combustion engines, producing continuous emissions. Traditional hybrids reduce emissions through energy-efficient management but still rely on petrol. Plug-in hybrids were marketed as a solution for longer journeys with reduced emissions; however, real-world usage often falls short of laboratory efficiency claims.

Petrol vs Hybrid: Key Differences

Feature	Petrol Car	Hybrid Car
Fuel Efficiency	16-17 kmpl (e.g., Hyundai Creta)	19-28 kmpl (e.g., Toyota Hyryder)
Emissions	Standard CO2 emissions	20-30% lower under ideal conditions
Performance	Higher top-end power	Brisk acceleration at low speeds due to electric motor
Cost	Lower upfront	₹200,000-300,000 higher due to battery and motor
Availability	Widely available	Increasing, but fewer options for large vehicles
Driving Experience	Conventional throttle response	Electric-petrol transition may feel unusual initially

Fuel efficiency is the primary advantage of hybrid vehicles. Regenerative braking, electric motor assistance, and the ability to shut off the petrol engine while idling help hybrids achieve significantly higher mileage.

Why Do Plug-in Hybrids Pollute Nearly as Much as Petrol Cars?

Despite expectations, plug-in hybrids often fail to deliver substantial reductions in real-world emissions. A report by the non-profit advocacy group Transport and Environment found that PHEVs emit only 19% less carbon dioxide than traditional petrol and diesel vehicles, far below previous laboratory estimates of 75%.

Researchers analysed data from onboard fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO2 emissions in 2023 were 4.9 times higher than laboratory tests suggested. The discrepancy largely arises from overestimating the “utility factor,” the proportion of miles driven in electric mode. The study found that only 27% of driving occurred in electric mode, compared to an assumed 84%.

Even in electric mode, PHEVs often burn fossil fuels for one-third of the distance because electric motors are insufficient for certain driving conditions. The gap between lab and real-world emissions has political and economic consequences, as carmakers have avoided substantial fines by complying with EU CO2 targets under false efficiency assumptions.

A separate study published in Environmental Research Letters in January 2024 emphasised that electrification is only as effective as the electricity grid. Cities powered by coal-heavy grids see smaller reductions in PM2.5, whereas a renewable-heavy grid maximises the environmental benefits of PHEVs and EVs. In India, Delhi, Mumbai, and Bengaluru would benefit most from cleaner grids, potentially improving public health significantly.

How Does This Really Affect You and Your Family?

Delhi’s residents face immediate health risks from high PM2.5 levels. Short-term exposure can trigger asthma attacks, bronchitis, cardiovascular events, and airway inflammation. While hybrid vehicles emit less pollution than conventional petrol cars under ideal conditions, the difference is modest in real-world urban driving.

Even small contributions from hybrids accumulate when thousands of vehicles operate daily in congested city conditions. Air pollution spikes can cause immediate respiratory and cardiovascular effects, particularly among children, the elderly, and people with pre-existing health conditions. The need to manage emissions from all vehicle types remains urgent to reduce these health risks.

If Hybrids Are Not That Effective, Is There a Better Option?

Fully electric vehicles (EVs) offer zero tailpipe emissions, representing a significant improvement over hybrids. Widespread adoption requires attention to grid emissions, charging infrastructure, and consumer behaviour. Policy measures such as improved public transport, carpooling incentives, and emission-based road taxes can reduce the overall number of polluting vehicles.

Renewable energy adoption for charging EVs ensures that vehicle electrification genuinely reduces urban air pollution. Strategic urban planning, including traffic management, low-emission zones, and expansion of green spaces, can further mitigate pollution exposure. Personal choices, such as reducing vehicle use or shifting to EVs, directly affect both individual and public health outcomes.

What Does This Mean for Car Owners or Residents?

Hybrid vehicles provide environmental benefits under certain conditions, particularly when regularly charged and driven efficiently. However, they are not a panacea for urban air pollution. Residents should consider commuting patterns, city infrastructure, and available vehicle technologies when evaluating options.

For Delhi-NCR residents, mitigating pollution exposure involves a combination of vehicle choice, behavioural adjustments, and support for broader policy initiatives aimed at cleaner energy and transportation solutions.

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