New Study Reveals PHEVs Emit More CO2 Than Previously Believed

A new study by the organization Transport and Environment (T&E) has unveiled that plug-in hybrid electric vehicles (PHEVs) produce carbon emissions comparable to traditional gasoline vehicles, challenging previous assumptions about their environmental benefits. The research, which analyzed 127,000 PHEVs registered in the European Union in 2023, found that these vehicles emit an average of 135 grams of CO2 per kilometer. This figure is more than 80% of the average emissions from petrol and diesel vehicles, which is 166 grams of CO2/km.

While electric vehicles (EVs) are often praised for their lower greenhouse gas emissions during operation, PHEVs present a more complex scenario. The study indicates that in real-world conditions, PHEVs emit nearly five times more CO2 than laboratory tests suggest. Manufacturers commonly claim that PHEVs reduce emissions by up to 75% compared to internal combustion engine (ICE) vehicles. However, T&E’s analysis shows the actual reduction is closer to 19%.

The distinction between PHEVs and traditional hybrid electric vehicles (HEVs) is critical. PHEVs have larger batteries that can be charged externally, allowing them to drive longer distances on electricity alone. In contrast, HEVs recharge their smaller batteries internally through regenerative braking. This reliance on gasoline engines under demanding conditions, such as high speeds and steep inclines, leads to higher fuel consumption and emissions.

When operating in electric mode, PHEVs can emit approximately 68 grams of CO2 per kilometer, which is about 8.5 times higher than predicted emissions. This discrepancy highlights the challenges in assessing the environmental impact of vehicles that are marketed as greener alternatives.

Understanding Emissions Across Vehicle Types

A broader analysis conducted by the Manhattan Institute two years prior revealed that lifetime greenhouse gas emissions of EVs and ICE vehicles vary significantly due to differences in upstream emissions. The research indicated that while EVs initially exhibit a higher carbon footprint due to the energy-intensive production of battery metals, they typically achieve lower lifetime emissions than ICEs after around 60,000 miles of driving.

Different methods of measuring emissions—such as tailpipe, well-to-wheel, and cradle-to-grave emissions—provide varying perspectives on vehicle impact. Well-to-wheel emissions account for the entire process of fuel production and use, while cradle-to-grave emissions consider all phases from manufacturing to disposal.

A study from the University of Michigan found that it takes about 1.4 to 1.5 years for electric sedans to offset their initial emissions disadvantage compared to ICE vehicles. For SUVs, the timeframe extends to 1.6 to 1.9 years, while pickup trucks require roughly 1.6 years. As per this research, emissions from battery electric vehicle sedans are about 35% of those from internal combustion sedans, while electric SUVs emit around 37% of gasoline-powered models’ emissions.

Despite the complexities surrounding emissions, studies consistently indicate that the greenhouse gas advantage of EVs usually surpasses that of ICE vehicles within a few years of use. As the automotive industry continues to navigate the transition to electric mobility, the findings from T&E and other institutions underline the importance of scrutinizing vehicle performance in real-world conditions.

The implications of this research are significant for consumers, policymakers, and manufacturers alike. Understanding the true environmental impact of PHEVs may influence decisions on vehicle purchases and shape future regulations aimed at reducing emissions in the transportation sector.