New Study Reveals PHEVs Emissions Are Near Gasoline Levels

New research from Transport and Environment (T&E) indicates that plug-in hybrid electric vehicles (PHEVs) emit greenhouse gases comparable to traditional gasoline vehicles. This finding challenges the perception that PHEVs are a significantly cleaner alternative to internal combustion engine (ICE) cars, raising concerns about their environmental benefits in real-world conditions.

The T&E analysis assessed data from approximately 127,000 PHEVs registered in the European Union in 2023. The study found that these vehicles emit an average of **135 grams of CO2 per kilometer**, which is more than **80%** of the **166 grams of CO2/km** produced by petrol and diesel vehicles. This stark revelation highlights that PHEVs can produce nearly five times the CO2 emissions in real-world driving compared to laboratory predictions, with actual emissions reductions being only **19%** versus ICE vehicles. This is a significant departure from the **75%** reduction figures often cited by manufacturers.

PHEVs differ from traditional hybrid electric vehicles (HEVs) in their battery capabilities. While PHEVs have larger batteries that can be charged externally, HEVs utilize smaller batteries that recharge through regenerative braking and the gasoline engine. This design allows PHEVs to operate solely on electricity for longer distances. However, the heavier batteries in PHEVs can lead to increased fuel consumption and emissions. Under certain driving conditions, such as high speeds or steep inclines, PHEVs activate their gasoline engines, resulting in fuel consumption of approximately **3 liters per 100 kilometers** even when in electric mode. Consequently, PHEVs emit **68 grams of CO2 per kilometer** while operating on electric power alone, which is about **8.5 times** higher than anticipated figures.

To contextualize these findings, two years ago, the **Manhattan Institute** published a comprehensive report comparing the lifetime greenhouse gas emissions of EVs and ICE vehicles. Although EVs generally have higher initial emissions due to the energy-intensive processes involved in battery production, they eventually achieve lower lifetime emissions when driven over extended periods. The report indicated that, in certain scenarios, the emissions from the dirtiest EVs could exceed those of the cleanest gasoline vehicles.

Vehicle emissions are categorized primarily into two types: air pollutants, which are harmful to health, and greenhouse gases (GHGs) such as carbon dioxide and methane. Emissions are evaluated on various bases, including tailpipe, well-to-wheel, and cradle-to-grave methodologies. Well-to-wheel emissions account for the entire lifecycle, from fuel production to vehicle use, while cradle-to-grave emissions encompass all aspects of a vehicle’s lifecycle, including manufacturing and disposal.

Notably, while studies have shown varying emission figures, they consistently find that the greenhouse gas emissions difference between battery electric vehicles and ICE vehicles diminishes within the first few years of an EV’s operation. Research from the **University of Michigan** indicates that it takes approximately **1.4 to 1.5 years** for EV sedans to eliminate the pollution advantage of ICE vehicles due to their manufacturing processes. For SUVs, this period extends to **1.6 to 1.9 years**, while pickup trucks take about **1.6 years**.

On average, emissions from battery electric vehicle sedans are approximately **35%** of those from internal combustion sedans, electric SUVs produce around **37%** of the emissions of gasoline-powered vehicles, and battery electric pickups emit roughly **34%** of the emissions of their ICE counterparts. All-electric vehicles, PHEVs, and HEVs generate lower tailpipe emissions than traditional gasoline vehicles, achieving zero tailpipe emissions when operating solely on electricity.

These findings from T&E and other research institutions underscore the need for more informed discussions about the environmental benefits of PHEVs. As the market for electric vehicles continues to evolve, understanding the real-world emissions implications is crucial for consumers and policymakers alike.