Regulators and policymakers must stop giving excessively beneficial treatment to plug-in hybrids, German researchers said, otherwise the cars will not make a meaningful contribution to tackling climate change.
According to a study, most plug-in hybrid cars are not more environmentally friendly than combustion engine models because of their limited full-electric ranges. If plug-in hybrids are not regularly charged, their CO2 emissions can be worse than a conventional gasoline or diesel car.
The conclusions provide more ammunition for critics of the technology, which has been embraced by automakers in Europe, particularly German premium brands, as an effective way to reduce CO2 emissions.
In what is described as the first systematic analysis into the actual benefits of plug-in hybrids, researchers at the Fraunhofer ISI institute and the International Council on Clean Transportation (ICCT) examined usage data from more than 100,000 vehicles across more than 66 different models sold in Europe, the U.S. and China.
At best, a plug-in hybrid produces average CO2 emissions that are twice as high as automakers claim, regardless of whether they are measured by the NEDC or WLTP test cycle. At worst, CO2 output from plug-in hybrids is four times above the certified figure. That means a plug-in hybrid with an official CO2 level of 50 grams per km actually emits between 100 and 200 g/km in operation.
Plug-in hybrids underdeliver on CO2 promise, report says
Mercedes offers 15 plug-in hybrids, depending on market, including this variant of the E-Class wagon.
Plug-in hybrids used as company cars are a big contributor to the problem, the research showed.
Not only are the cars driven distances that exceed their limited electric range, they also charged every other day on average. In addition, company car drivers are economically incentivized to fill up the vehicle because their employers pay for the fuel.
"If we want to see lower fuel consumption and CO2 emissions in real life, the engine’s horsepower needs to be reduced and the electric range increased," Patrick Plötz, the lead author of the study, told reporters.
He estimates the range would need to be between 80 km and 90 km, compared with the 30 km to 60 km certified under NEDC tests, for a plug-in hybrid to largely replace the combustion engine mileage driven annually by a motorist in Germany.
The authorities, meanwhile, must adapt the coming 2025 supercredit system, which encourages plug-in hybrids, to weed out ineffective models with low ranges and high horsepower, the researchers said. They recommend the EU tailor the credits on the anonymized data collected from fuel consumption monitors. These are mandatory for all new cars as of January under the Euro 6d FCM-ISC standard.
Moreover, they suggest that plug-in hybrid incentives for company car be issued only to organizations that provide a sufficient workplace charging infrastructure or support employees’ efforts keep their cars charged.
The findings are particularly controversial given that automakers have cited research by Plötz from November 2017 as proof that plug-in hybrids are good for the environment.
As recently as this September, Volkswagen pointed to his work -- titled "Plug-in hybrid vehicles are better than their reputation" – as proof that it is a "myth" that drivers do not charge their vehicles.
The Fraunhofer researcher said automakers failed to mention that the older study was not designed to provide a comprehensive and definitive conclusion. That was part of the motivation to revisit the subject three years later.
"At the time, we looked solely at the number of kilometers driven electrically," Plötz told Automotive News Europe. "We did not examine the deviation from the test cycle, and that is where these unflattering results can be found."
His new findings support suspicions that plug-in hybrids are so-called "compliance cars," which means they are fuel-efficient on paper but emit just as much CO2 as conventional models.
The ramifications of the growing collection of negative results for plug-in hybrids could be far-ranging. Reducing CO2 emissions from vehicles is a fundamental pillar in an overall package of laws designed to cut the European Union’s 2030 annual carbon footprint by 55 percent compared with 1990.
Road transport is responsible for a fifth of the EU’s overall emissions. And while the utilities and agriculture sectors have cut their CO2 levels, the transportation sector has failed repeatedly to lower its emissions in the past three decades.
Critics such as the Brussels-based green lobby group Transport & Environment blame this failure on certified fuel consumption figures not translating into real life use. T&E has called plug-in hybrids the worst example of this discrepancy.
If these vehicles do not cut real world CO2 output, regulators are legally required to take steps to ensure the EU delivers on its obligations under the Paris climate accord.
A plug-in hybrid crackdown would have a dramatic effect on sales. After the Netherlands slashed incentives for plug-in hybrids, their sales collapsed from an EU-best 40,000 in 2015 to just 1,150 two years later.
To date, more plug-in hybrids have been sold in Europe than anywhere else. The 780,000 sold cumulatively through 2019 eclipsed China by about 10,000 units, according to the International Energy Agency.
Further strong growth looks likely to cement that status. Europe’s auto industry body, ACEA, reported recently that registrations of new plug-in hybrids in Europe nearly tripled in the first two quarters. Volumes, however, are heavily concentrated in a handful of markets including France, Sweden and the UK. Each country recorded sales of about 20,000 units during the period.
Leading the way, however, is Germany. With more than 49,500 registrations, it accounts for 28 percent of Europe’s plug-in hybrid sales. This is in part due to the very generous subsidy – 6,750 euros off a car with a list price of less than 40,000 euros before tax. This has put Germany on track to be the country with the most plug-in hybrids sold this year after China.
"Plug-in hybrids can serve an important role electrifying the fleet so long as they are largely driven electrically," said Peter Mock, head of the ICCT in Europe. "To achieve that, regulations need to be changed since they currently are not providing a sufficient incentive to recharge."
