Plug-in hybrid vehicles are often touted as a bridge to battery electric vehicles, promising to reduce emissions by operating as EVs for short trips while relying on fossil fuels for longer ones.
They only fulfill this promise if they are charged regularly. Real-world data gleaned from vehicle onboard computers shows that this is often not the case.
Using this data, the Fraunhofer Institute could determine how much of a vehicle’s energy use came from charging as opposed to the internal combustion engine. The found that Grid power was responsible for less than a third of a vehicle’s total energy use. The vast majority of the 1 million PHEVs in Germany were plugged in either occasionally or not at all.
American automakers promoting future PHEV models as attractive alternatives to American drivers should take note. By blending natural gas with electricity, these automakers hope to boost fleet-wide efficiency without widespread EV availability.
“We are looking to fix the CO2 reductions across our range, but we’re doing it in a very efficient way,” said Ford CEO Jim Farley he said this month on an earnings call.
However, the new study shows that PHEVs rarely deliver on their efficiency promises.
At best, Toyota drivers used electricity for 44% of the energy they used to drive, suggesting they plugged in more often. The worst? Porsche drivers, at just 0.8%, average 7 kilowatt hours over two years. In other words, the average Porsche PHEV driver charged his battery to less than 50% of its capacity — once.
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Studies have previously shown that PHEVs produce approx 3.5 times more emissions than their official ratings suggest. This new study explains why by directly assessing how much electricity the vehicles gained from charging. (PHEVs, like all hybrids, can run in mixed mode, using both natural gas and electricity. The study used data directly from the vehicles to disentangle the two.)
One of the many disadvantages of PHEVs is their anemic batteries, capable of powering the vehicle for short distances. Some can only travel a handful of miles, while many sold in recent years can run on battery power for about 20 to 30 miles. Regulators in Europe and automakers are proposing longer ranges for future models, hoping a more capable battery will encourage people to charge their batteries more often.
This is not guaranteed, however. Vehicles are likely to remain at risk when driving with electrons. This is because most PHEVs are based on fossil fuel platforms — electric motors and power electronics are not capable of meeting 100% of the vehicle’s power needs. When the driver lowers it, the gas engine should kick in. In other vehicles, the engine starts in cold weather to heat the cabin. When that happens, “why bother plugging in” is obviously a question most PHEV drivers have asked themselves.
Which raises another question: Why bother with PHEVs at all?
PHEVs have been touted as a way to ease cautious consumers into full EVs. The argument goes something like this: Drivers will get used to plugging in while EV charging networks are built. By the time they are ready for their next vehicle, the networks will be ready and customers can switch to an EV.
But if no one is plugging in their PHEVs, they certainly aren’t developing the habit. Without full charges, the electric powertrain does no one any good. The public still suffers from the worst air pollution and drivers carry hundreds of kilos and endure more recalls and more expensive service visits as a result of the complex drivetrain.
Adapting the PHEV formula to be more battery-dependent could help. The intermediate solution is called an extended-range electric vehicle (EREV) and is designed to run on battery power until the charge runs out, at which point the fossil fuel engine recharges it. So far, no EREVs have required the owner to plug in — they could easily drive the vehicle for its entire life on gas. BMW used to build an EREV in the i3, but stopped production years ago. Ford and Stellantis both announced EREV pickup trucks, which have yet to be released.
Meanwhile, EV charging networks continue to expand. It’s likely that once automakers build PHEVs and EREVs in large numbers, drivers will no longer need a comfort blanket in the form of a gas engine. (My household came to this conclusion two years ago. After a decade split between a BMW i3 EREV and a Chrysler Pacifica Hybrid PHEV, we traded in a Kia EV9.)
Legacy automakers, which have second-guessed their electrification strategies more times than I care to count, could be forced to change course once again.
PHEVs may have been a great solution on paper, but they failed to deliver in the real world.
Update 2/25: Clarified how much power from chargers was used by PHEVs in the study.
