Plug-In Hybrids May Actually Be Worse For The Environment

Electric Vehicles / 16 Comments

Why? Because owners are not using them properly.

Plug-in hybrid vehicles like the new 2023 Toyota Prius Prime are a great stop-gap for drivers who aren't fully ready to embrace electric vehicle ownership. Most offer around 20 to 30 miles of all-electric range, meaning owners can do their daily commute to work and only use gasoline on the weekends for longer trips. That's great in theory, but a new study from the International Council on Clean Transportation (ICCT) shows that PHEV owners are not plugging in their cars as much as regulators predicted.

Using self-reported fuel consumption data from and engine-off distance traveled collected by the California Bureau of Automotive Repair (BAR), the study estimates that the number of electric miles driven by PHEV owners is anywhere between 25% to 65% lower than the EPA labeling program suggests. Without being plugged in daily, real-world fuel consumption is around 42% to 67% higher.

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PHEVs can achieve excellent fuel efficiency when plugged in daily because they can shut off the engine and burn no gasoline. However, when they are driven around on an empty battery, the engine is forced to lug around the weight of an electric motor and battery without being able to rely as heavily on them compared to a standard hybrid. According to the study, early PHEV adopters have easy access to charging but more recent owners may not have access at their residences.

"The datasets analyzed here are comprised of a variety of models of comparable sample sizes, which strongly suggest widespread deviation from EPA label electric drive share. However, as PHEVs are still a small share of the existing fleet and new sales, all data sources to date may be inherently biased towards early adopters," the study reads.


The study suggests that the EPA should take a closer look at PHEV owner driving habits using "on-board diagnostic reporting requirements." It also recommends a minimal electric range requirement similar to the zero emission credits in the Advanced Clean Cars II regulation. Adding requirements such as minimum electric power/range, maximum fuel tank size, fast-charging, and minimum cold weather performance could greatly improve PHEVs beyond their current usefulness.

We'd personally like to see more PHEVs offering 40-50 miles of electric range, rather than the 20-30 that's common now. Brands like Volvo have made huge strides, upping the range for its plug-in Recharge models. PHEVs are also more confusing to operate than a standard hybrid or even an EV, so there needs to be better eduction from dealerships during delivery.

2018-2020 Volvo S90 Hybrid Electric Charging Volvo
2023 Kia Sportage PHEV Charging Point KIA

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