Governors' Biofuels Coalition

A global shift toward zero-emission vehicles is taking longer than expected, complicating efforts to decarbonize road transport and alleviate urban pollution. The car industry is pushing a stopgap solution: hybrid vehicles that combine a traditional internal combustion engine with batteries and electric motors.

The idea appears to have won over the European Union, which in December abandoned a quasi-ban on combustion-engine cars set for 2035 and gave hybrid vehicles a key role in its push to achieve net zero carbon emissions by 2050.

Hybrids have been gaining in popularity among buyers looking to cut their emissions and running costs without committing to a fully electric vehicle, which is often more expensive due to its bigger battery. But the environmental credentials of hybrids are open to debate due to discrepancies between emissions in lab tests and the real world.

What is a hybrid car?

A hybrid electric vehicle, or HEV, has an engine working in tandem with one or more electric motors. The pairing can improve fuel efficiency, mileage and acceleration. Because the engine can be smaller and run less frequently, hybrids produce fewer tailpipe emissions than a traditional gasoline or diesel car.

Early examples of mixed-power cars date back to the early 20th century, but hybrids didn’t become mainstream until the late 1990s when Japan’s Toyota Motor Corp. began selling the Prius. As the world’s first mass-produced hybrid, it helped normalize the idea of electrified driving long before widespread charging networks existed.

What kinds of hybrids are there?

Most hybrids, including the Prius, have complex transmission systems that blend power from their combustion engine and electric motors. Their batteries are charged partly by the engine and from energy captured during braking that would otherwise be lost when the vehicle slows down. Plug-in hybrids, or PHEVs, take things further by allowing drivers to charge the batteries from a socket.

Hybrids tend to use their electric motors most on trips through urban areas that involve a lot of stopping and brief accelerating, and rely more on the engine when traveling at higher speeds.

In another type of hybrid, known as an extended-range EV, or EREV, the electric motor drives the wheels and the gasoline engine acts solely as a generator that keeps the battery topped up. This layout was used in early hybrid models such as the Chevrolet Volt more than a decade ago. Chinese carmakers have revived and refined the approach, developing EREVs with far longer ranges and more efficient generators.

Why are hybrids growing in popularity?

For much of the past decade, the rapid growth of fully electric vehicles led many in the industry to assume hybrids would play only a brief role in the shift to cleaner transportation. EV-focused automakers led by Elon Musk’s Tesla Inc. dominated the narrative as sales of fully electric cars began to accelerate.

From around 2023, EVs needed to start luring more cost-conscious buyers in Western markets to maintain their growth momentum. But they’ve proved too expensive for many drivers. What’s more, most lack the range of traditional gasoline-powered cars and there’s a dearth of available recharging points in much of the world. Some buyers have also wavered on EVs because of concerns that the batteries may have a limited lifespan.

So growing numbers of drivers are turning to hybrids, seeing them as an affordable way to achieve meaningful emissions reductions without forcing them to change where or how they refuel.

Several governments have weakened incentives and regulations aimed at spurring uptake of EVs. As a result of policy swings and disappointing demand for their early EV offerings, Western automakers such as Ford Motor Co. and Volkswagen AG are scaling back their EV efforts and spending more on hybrids. Asian players such as Toyota and Honda Motor Co., which never abandoned hybrids, find themselves increasingly aligned with shifting consumer sentiment. In Europe, hybrids have taken off fastest in southern markets where EVs remain expensive and public charging is still patchy.

Are hybrids really a green option?

Hybrids were once lauded as an essential stepping stone toward carbon neutrality but their ecological appeal diminished when sales of fully electric vehicles really took off around the turn of the decade. What had been celebrated as a valuable transitional technology came to be viewed increasingly as a crutch for legacy car brands unwilling or unable to make the leap to full electrification.

Toyota, the company that pioneered the technology, has been widely criticized for sticking with hybrids as it resisted the shift to EVs. The Japanese carmaker argues that the world lacks the resources to go all-electric as quickly as policymakers hope, and that a “multi-pathway” approach — offering hybrids, hydrogen fuel cell vehicles and EVs — will reduce emissions faster in the meantime.

Climate campaigners are skeptical of this view. They argue that gasoline-electric cars aren’t as eco-friendly as their makers claim, as it’s not always clear how often or how much a hybrid is running on electricity versus burning gasoline. Plug-in hybrids are a particular source of tension: Studies show many drivers rarely charge them, meaning the vehicles often operate like conventional cars while dragging around heavy unused batteries.

Campaign group Transport & Environment said data from thousands of vehicles showed that PHEVs emit just 19% less carbon dioxide per kilometer, on average, than petrol and diesel cars. In the real world, CO2 emissions from plug-in hybrids are almost five times what official tests suggest, according to T&E.

BNEF said the EU’s vehicle emissions testing system is being updated. The outcome could be decisive in determining how many hybrids carmakers will be allowed to sell in the bloc as the share will depend on average PHEV emissions.

Why wouldn’t you charge your plug-in hybrid?

The reasons are often practical. Company-car drivers in Europe, who make up a significant share of PHEV owners, often have their fuel paid for by their employer, while electricity for home charging typically falls on the employee. That imbalance leaves many drivers with little financial incentive to plug in.

A lot of urban residents cannot charge at home, and big increases in household electricity bills in some markets have sometimes made charging costlier than filling up at the pump.

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