A new study shows that the gap between real-world pollution from plug-in hybrids and official government estimates is getting wider – and worse, plug-in hybrids themselves are getting dirtier.
And the car lobby is trying to hide it, and make it harder to regulate the pollution coming out of these vehicles.
The evolution of transportation takes many forms, and we here at Electrek like to cover most of them. It leads to all sorts of weird acronyms – BEV, PHEV, EREV, FCEV, HEV and so on.
Here, we’re talking about the PHEVs. Plug-in hybrid vehicles.
PHEVs are cars that have a significantly sized battery which can be filled up by plugging in, unlike conventional hybrids, which get all their energy from gasoline and merely recapture some of it during braking. Some have bigger batteries than others, but most of them can run on pure battery mode at least for some reasonable number of miles.
Plug-in hybrids are often thought of as a “transitional” technology between fully fossil-powered vehicles and fully electrically-powered ones, because you can use either as a fuel source. More flexibility means you can use whatever fuel source is more convenient for your current application.
It seems like a “best of both worlds” situation at first look… but there are downsides. PHEVs are more mechanically complex, and often one or both of the powertrains will be cobbled together as an afterthought, leading to a compromised vehicle overall.
And then, there’s the pollution, which turns out to be far higher in the real world than anyone wants to admit.
We’ve covered many, many studies showing that PHEVs are dirtier than expected, and now Transport & Environment (T&E) is out with a new update showing that not only is the gap between real-world and laboratory emissions growing for EU PHEVs, but PHEVs are getting dirtier over time, rather than cleaner.
PHEVs are now 6x dirtier than testing indicates
The analysis is an update of T&E’s previous work, showing a trend of PHEV emissions testing estimates getting less and less realistic over time.
The new update uses data from 220,000 PHEVs in Europe. Europe has mandated fuel use monitoring on vehicles, called the “On Board Fuel Consumption Monitoring” (OBFCM) system. This allows for much better real-world data, which can then be compared against laboratory data to see how cars use fuel in the real world, rather than tests (which, as we have learned, can be gamed).
T&E analyzed this data and found that PHEV emissions rose from 138 gCO2/km in 2023 to 145 gCO2/km in 2024, an increase of 5% in a year. Needless to say, this is going in the wrong direction.
In fact, 145 gCO2/km is only 14% less than the average for fossil-fueled vehicles, meaning in the real world, PHEVs are only barely cleaner.
Not only is this going in the wrong direction, but government testing indicated over the same period that PHEVs should have gotten cleaner. But in the real world, they didn’t. So what’s going on here?
It’s about “utility factors”
Since PHEVs have two powertrains with vastly different pollution profiles (one of which produces no tailpipe pollution, and one which is responsible for the hurricanes and wildfires ravaging the planet and millions of deaths per year), any testing has to estimate how often you’re going to use each of those powertrains.
So government includes a “utility factor” calculation for how often it thinks battery power will be used. And those utility factors are way, way off.
It turns out that people just don’t plug PHEVs in. (Although, that said, even when running on electric mode, PHEVs use 3x more gas than claimed)
This happens for various reasons, and the amount that it happens differs from territory to territory and from car to car. But in every study we’ve seen, whether in EU (where OBFCM data is available, and thus these studies are more common) or in the USA, the common fact is that tests always underestimate the pollution that PHEVs put out. On the better-designed PHEVs, if you do plug them in all the time, they can be much cleaner than a gas car… but people just don’t do it.
Car lobby wants to keep numbers wrong to keep selling you engines
With all these studies showing PHEVs to be dirtier than we thought, it would make sense for government to act and fix the estimates (and for automakers to make PHEVs that are more worth plugging in, as some of the above-linked studies have suggested).
Updating testing is precisely the plan – as the gap between testing and real-world emissions has been rising, the EU has planned to update “utility factors” to better reflect the reality of how people use their vehicles.
But the problem with that is that if Europe finally more realistically accounts for the real-world pollution coming out of these vehicles, auto manufacturers wouldn’t be able to get as much unearned “extra credit” for selling polluting gas-powered cars with a small battery and plug attached. This would be a threat to their greenwashing, and they can’t have it.
So automakers have consistently lobbied the EU to weaken updates to utility factors, which would allow their vehicles to continue polluting, but allow them to continue patting themselves on the back for greening their fleet when they have done no such thing.
Test numbers don’t matter, the real harm done is what matters
To be clear: pollution matters in the real world because of the health problems it causes for everyone, and because of its contribution to climate change. Neither of those damages care about what the gamed testing numbers say. If you breathe pollution, you breathe it either way, even if the automakers lie to you and tell you that the air was clean.
We’ve been through something similar before – Dieselgate. In that instance, VW (and, uh, basically everyone else) lied to the tests while polluting more in the real world. This is part of why we have OBFCM in the first place – so we don’t have to rely on the tests, and we can know what’s going on in the real world. And here we are, just a decade later, falling to the same lies.
Further, as pointed out by Lucien Mathieu from T&E, these sorts of delays harm the European auto industry.
“Plug-in hybrids are one of the auto industry’s greatest greenwashing stunts – marketed as a green solution, yet delivering a heavy environmental toll in practice. They are also a major rip-off for consumers, who end up paying far more for fuel than expected. Carmakers are demanding that the EU turn a blind eye so it can delay investing in fully electric cars. Utility factors were designed to make official emission match with real-world; they are evidence-based policy making. If Europe wants to keep a chance to compete with China in the global EV race, it must resist any attempt to weaken the utility factors.”
Automakers have used this PHEV “extra credit” to delay deploying pure EV cars – they’ll add a small battery to an ICE car, get bonus points for doing very little, and continue on without updating their cars to what the state of the art of the industry can actually provide. Meanwhile, Chinese automakers are rapidly deploying new EVs, and those are gaining share in Europe and across the glove rapidly, displacing European-made cars. If Europe wants to keep up, it needs to stop deluding itself and start confronting reality.
Can we please learn a lesson for once, and stop trusting the automakers when we know they’re lying?
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