Automakers often claim that plug-in hybrids are their stepping stone toward full electrification because they combine the quiet, zero-emission operation of an electric vehicle with the comfort and ease of a gasoline or diesel-powered car. This has contributed to a growing number of PHEV sales in Europe, where stricter emissions regulations are forcing companies to build more and more of these vehicles as a stopgap measure.
Of course, we know that the environmental credentials of PHEVs aren’t quite as compelling as automakers would have us believe, as the driving habits of actual buyers vary greatly from, say, them. optimistic Nature of laboratory-based driving cycles such as WLTP. But a new study by the European Environment Agency (EEA) has made it clear how big the gap is between claimed fuel consumption values and actual consumption.
Crucially, the EEA received data on on-board fuel consumption monitoring devices supplied by car manufacturers and installed in vehicles sold in the EU – a requirement as part of WLTP certification. While this gives manufacturers some leeway to manipulate the data, it means that the data reflects real-world usage by actual customers and not just another test conducted by experts.
In total, the EEA received data from 988,231 vehicles (including 916,216 cars and 12,301 vans) out of a total of 9,821,479 vehicles registered in the EU, Iceland and Norway in 2021 – the first year in which the above-mentioned measuring devices were mandatory. The agency said the study aims to measure the discrepancy between WLTP and real-world fuel consumption and carbon dioxide emissions and to suggest ways to make the WLTP cycle more realistic.
The EEA found that vehicles with internal combustion engines recorded fuel consumption of 7.88 liters per 100 km, while the reported WLTP average was 6.13 l/100 km. This suggests that drivers consumed around 1 to 1.5 l/100 km more than official estimates. A similar gap existed between real (180.3 grams per kilometer) and WLTP (148.8 g/km) CO2 emissions, a difference of 21.2%.
This gap widened into a gap for PHEVs, which recorded a whopping 3.5 times (252%) higher fuel consumption (5.97 l/100 km) and CO2 values2 Real-world emissions (139.4 g/km) compared to claimed WLTP averages (1.69 l/100 km and 3.96 g/km respectively). The EEA said the result showed that plug-in hybrids were being charged and driven in electric mode much less often than expected and that the assumptions used to calculate the WLTP test did not correspond to real-world conditions.
The good news is that despite fears that PHEVs are more polluting than pure combustion vehicles, the study showed that plug-in hybrids still offer a net benefit. Compared to their gasoline and diesel-powered counterparts, they were able to use less fuel and emit fewer emissions on average – although only by an average of 23%.
Some PHEVs performed better than others. For example, Kia’s plug-in hybrids built in Slovakia (i.e. Sportage and Ceed) consumed on average only 3.87 l/100 km and produced only 88.13 g/km CO2. That’s still a big jump from the WLTP estimates of 1.48L/100km and 33.72g/km respectively, but it’s still impressive and proves that these cars were either more efficient or their owners were more careful about charging . However, this is a relatively small sample – only 82 cars were registered here.
On the other hand, luxury and high-performance PHEVs were the worst offenders on the list, negatively impacted by the relative inefficiency of their two cars, shorter all-electric range ratings, and their owners’ lack of attitude towards charging. Porsche’s PHEVs had an average fuel consumption of 10.79L/100km against the WLTP estimate of 3.03L/100km, while the sole Bentley PHEV listed in the study had an average consumption of 12.97L/100km had the WLTP estimate of 3.6 l/100 km. 100 km.
The worst of the worst, however, was Ferrari. His 296 GTB and SF90 Stradale/Spider averaged a shocking 20.06L/100km, while the average WLTP figure was 6.88L/100km. This isn’t exactly surprising since their electric motors are used primarily to increase performance rather than reduce fuel consumption. What’s even more surprising is that they uses a lot more fuel than even Maranello’s notoriously gas-guzzling petrol-only models, which only consumed an average of 16.28 l/100 km. Ouch.
These figures are consistent with the EEA’s findings that heavier internal combustion engine vehicles such as SUVs and luxury cars produced 1.5 to 2.5 times more carbon dioxide emissions than claimed, compared to a difference of 20 to 40 g/km for lighter vehicles. This is in addition to their already higher WLTP CO emissions2 Emissions levels are falling and, given the general industry trend towards larger and heavier vehicles, the efficiency gains achieved are being offset.
For its part, the EEA explained that it is still too early to identify trends in fuel consumption and variations in emissions as the registered vehicles have only been on the road for a year. However, the gap for PHEVs is huge and the EU is already changing the way these numbers are calculated for plug-in hybrids. These changes will be implemented in two steps from 2025 and 2027.
So remember, folks: Just because you bought a plug-in hybrid doesn’t mean you’ll automatically save fuel. Fuel cost savings and emissions reductions depend heavily on how often you plug in your car to charge. If you don’t, you may even end up using more fuel and polluting the environment more than if you had just bought an internal combustion engine car.
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