Plug-in hybrids underdeliver on CO2 promise, report says

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.