We have a problem in Australia with testing the CO2 emissions of plug-in hybrids (PHEVs). I have had an interest in this topic for some time, but the more I’ve followed what is happening in the European Union (EU), the more worrisome the Australian situation becomes.
It’s fairly well understood that the emissions from PHEVs are highly dependent on the behaviour of the driver – much more than for a conventional combustion engine vehicle, or indeed an EV.
Just because you have charge in your battery doesn’t guarantee the combustion engine won’t start under load. To really get an environmental and financial benefit from a PHEV, the driver must charge the battery scrupulously after almost every trip to minimise fuel use.
Thinking that buying a PHEV is going to automatically slash your tailpipe pollution is like thinking that buying a gym membership is automatically going to make you fit. You actually need to be committed to doing some work.
Australia currently tests vehicles for CO2 emissions using the New European Driving Cycle (NEDC). The NEDC test for PHEVs was devised before there was any significant experience with these vehicles.
The NEDC simply assumes that every driver operates their PHEV the same way: deplete a battery from fully charged, drive it a further 25 kilometres using fuel, and then plug it in to re-charge.
If you have a driver who rarely plugs it in, the real-world emissions of the vehicle are much higher. Even a diligent ‘plugger’ will have much higher emissions if they do even a few long-distance trips. The NEDC model is simple but it’s clearly flawed.
With the introduction of the New Vehicle Efficiency Standard (NVES), Australia is moving over time to the Worldwide Harmonized Light Vehicles Test Procedure (WLTP). This improves the procedure for testing PHEV emissions by applying so-called utility factor curves.
These curves specify, for a given electric range, the fraction of electric operation. The logic goes that the larger the battery, the greater the proportion of time the vehicle will spend in electric operation, until a point. Three utility factor curves are shown in the following figure and will be referred back to later. The red curve is the one that is applied in Australia today.
Source: J. Dornoff/ICCT (2022), “Euro 6e: Changes to the European Union light-duty vehicle type-approval procedure”
Every new vehicle sold in the European Union from 2020 must be equipped with on-board fuel consumption monitoring and the data collected over-the-air or when vehicles are serviced. Data are now available for 2021, 2022 and 2023. The European Environment Agency has been able to determine the gap between the rated and actual emissions of PHEVs as follows:
Source: European Environment Agency, “Real world CO2 emissions from new vans and cars”
You may ask, how can this percentage gap be getting wider? Aren’t the batteries in newer PHEV models entering the fleet in 2022 and 2023 larger, allowing drivers to travel further on electricity and less frequently using the combustion engine?
The answer is that while newer PHEV models do have larger batteries, this gives them an even more optimistic emissions rating than before. They also achieve poorer economy when driving on fuel due to the increased battery weight. If a vehicle is still not plugged in regularly, then this gap becomes wider.
Recognising this unacceptable situation, the European Commission commenced an interim regulation in January this year called Euro 6e-bis. This regulation improves the accuracy of PHEV emissions testing by adjusting the utility factor curve (see tan curve in the chart).
In 2027, another revision of the regulation (Euro 6e-bis-FCM) will come into force which further improves the emissions ratings to reflect the actual fuel consumption data (see cyan curve in the chart). For a PHEV with 100 km of electric range, the original (red) utility factor curve from Euro 6d assumed about 90% electric operation.
With the 2027 regulation, that same vehicle will be assumed to have a bit over 40% electric operation. That may seem low but one long trip mostly using fuel cancels out many weeks of purely electric local driving. The 2027 standard is expected to produce values acceptably close to real-world emissions, but may still be amended in future.
The effect of these changes is substantial. In an International Council on Clean Transportation policy brief, the CO2 emissions rating for a popular plug-in hybrid with 70 km of electric range was re-calculated using the Euro 6e-bis and 6e-bis-FCM regulations.
Its rating increased from an initial 45 g/km by the Euro 6d standard to 96 g/km (Euro 6e-bis) and up to 122 g/km by the most realistic Euro 6e-bis-FCM standard.
That’s nearly three times higher than the original rating and comparable to many non-pluggable hybrids on the market. Given this new rating, if you want a low emissions vehicle, you will need to buy a proper battery EV.
If we don’t have realistic ratings for plug-in hybrids, they will undermine the integrity of the NVES by allowing importers to claim spurious credits for PHEVs sold with artificially low CO2 emissions ratings while, in practice, they will pollute much more.
This will become the next failure among several in emissions accounting. Consumers will also be misled by the advertised fuel consumption figures that are so low they are rarely achieved in practice. Vehicles often fall a little short of the fuel economy shown on the windscreen sticker, but these discrepancies are next level.
The EU is acting decisively to remedy this flaw in PHEV emissions testing and so must Australia. The Australian Government, having spent a couple of years in the trenches over NVES, is being slow to react to this problem and needs to swiftly adopt the improved test procedure for plug-in hybrids.
Ben Elliston is the chair of the ACT branch of the Australian Electric Vehicle Association (AEVA). Opinions expressed in this article are his own and not necessarily those of AEVA.
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Thanks Ben, for illuminating this situation. How much time is it likely to take the Australian Government to take on this new data, and adopt the new system that the EU is now applying? It's feeling a lot like carbon credits 2.0.
So hybrid is bullshit. We all know this. Thanks Ben for gathering the data!
Hybrid is not necessarily bullshit, but the ratings claimed by manufacturers is definitely bullshit. This is a continuation of the misleading L/100km.
There is a simple solution. Meter to measure generation of emissions. These should not cost very much at all. Governments around the world should demand this as a standard fitting.
If manufacturers can't or will not enable this then retailers can be required to install a solution that may involve connection to a basic mobile phone that forwards the information. If it costs more than a few hundred $s a default could be based on government one of measurement of emissions.
Thanks to Herv I looked up details and my last paragraph is redundant.
The point is that ratings on PHEVs are particularly unreliable, very much more so than for other vehicle types, whether plain hybrids or battery EVs or ICE vehicles.
Yep, PHEV is a joke of a vehicle unless there isn't a suitable BEV equivalent such as what the Australian market has with the BYD Shark presently.
The driver is either diligently charging and discharging each day, driving with battery only or they have reduced their fuel consumption slightly in hybrid mode. Eitherway its the wrong vehicle to own and drive. $50K plus for a PHEV with about 80km of range.
If only Rivian & Slate could build a plant in SE Asia for the RHD market using LFP batteries.
I'm averaging 4.3L and most my tanks are under 3L in the shark. 15,000km done.
In regards to NVES credits a vehicle should be registered with the worst case scenario (running on fossil fuel only), end of story. If the owner wants to charge and run it on EV mode all the time good for them.
Of course hybrids are BS. The Toyota hybrid does about 2km on its battery. Of course there are loopholes. Got to look after corporate mates, cough, donors.
Toyota hybrid Yaris.
To be fair, I could get 850 kms out of a 36 litre(?) tank on my hybrid Yaris ZR. I only filled it up once every few months.
I'm not a fan of hybrids but if I had a PHEV the economics of running it would have me doing all my shorter trips on battery only. I'm not sure why you'd buy one then not bother using it.
On the other hand, I have no idea how many PHEVs are fleet vehicles (AI says they're popular fleet choices, for what that's worth) ... but what incentive would a driver of a fleet car have for ever topping up the battery either at home or at a fast charger?
Take away the fuel card so they have to charge (and can claim that) and if they want petrol they pay for it out of their own pocket.
Check out ADR 112/00 – Control of Real Driving Emissions for Light Vehicles 2024. Its a on-road driving test with a PEMS. The vehicle has to be running in Charge Sustaining mode (hybrid) and that should capture the emissions better from a PHEV.
Its all starting from the 1st December 2025.
Whether that feeds into the NVES I have no idea.
Herv. Great work.
Excited that new standards apply from December. More so the new standards are stricter than EU. Also to some extent the new higher standards that match Japanese standards - can you believe it?
The pages I found below with ? instead of full stops in the link - replace with a full stop to use:
infrastructure?gov?au/questions-and-answers-new-adrs-light-vehicle-noxious-emissions
and
legislation?gov?au/F2024L00447/latest/text
The second link is a bit of a read but easily searched if you know what you want to find. There is also quite a bit worth reading just for background info.
Yep, I did read a lot of the legislation about a week ago. Its what one does on a lazy Saturday afternoon?
I'm hoping it'll force a proper update to the Green Vehicle Guide since it seems to be the go to for a lot of people. Their emission data is completely wrong.
I roll my eyes every time someone points to GVG but not understanding their underlying data is out of date or just wrong.
That is about noxious emissions (CO, NOx, particulates etc), not greenhouse gas emissions (CO2). The NVES is about gradually reducing the average CO2/km rating of new cars.
Did you read the legislation? You should go read it. Then you might want to change what you just typed.
Long time PHEV driver here, as well as diligent plugger-inner, and the tan line is almost bang on what our real world experience has been. As the article says, the red line is obviously wrong given occasional longer trips make up a disproportionately large fraction of total kilometres (and fuel use). The blue line is a concern as it implies people not diligently plugging in, which is likely to be those buying for the sticker claims rather than real world benefits, and we'll need to educate and manage those.
In our house we also have a BEV. Interestingly since the PHEV is larger and does all the heavier work, with just under half its usage being electric at just over double the rate of consumption, it still eliminates just as much petroleum as our BEV does. I totally agree a realistic understanding of utility factor is needed to properly quantify the proportional benefit of PHEV, but the baseline consumption of the vehicle being replaced matters equally too. We will most likely buy another PHEV to replace it as it's most fit-for-purpose in our heavy use case given limited BEV choices.
People on here argue that the long term benefits of bevs render them a lay down misère.
Apart from 'monster trucks,' aren't there enough equivalent new bevs out there? Or are they just overpriced and ouside your budget?
"Equivalent" is a combination of utility and price for all buyers, and it is certainly my view that there are not enough equivalent new BEVs out there yet. For BEVs it is also a function of the available infrastructure depending on your location, another factor in our case.
I'm a shark owner and have done 15,000km. At least half is on the highway and there have been 8 or 10 trips over 400km. My average is 4.3L/100 and most tanks are under 3L/100. I do charge every day off solar.
You will find most Shark owners are very conscious about charging if they can but there are a small amount that can't or those that do lots of long trips or tow. Overall the sharks average emissions would be a fraction of legacy diesels and larger American utes.