Since the German government started handing out big subsidies for the purchase of battery-electric vehicles, sales figures have increased significantly. But electric cars only make up 1.2% of the country's total registered stock of around 48 million vehicles.

An important reason for this, in addition to high prices and a shaky charging infrastructure, are considerable doubts about the much touted environmental friendliness of electric vehicles.

"For me, the alleged CO2 balance is just a swindle. You definitely can't save the environment or the climate with an electric car, especially not with Germany's electricity mix," wrote one reader last week in the online comment section of a major daily newspaper.

Electric cars are on the march

"The criticism of electric cars is usually ignited by two points. One is the energy-intensive production of the battery, and the other is the proportion of electricity still made with fossil fuels," Hinrich Helms, an expert on alternative drive systems at the Heidelberg Institute for Energy (ifeu), told DW.

In addition to his own modeling of the environmental balance sheet of electric cars, he has also evaluated studies by other institutions on the subject.

In large parts of the research sector, there is a consensus on the climate assessment of electric cars. Taking into account the most important factors that play a role in production and operation, today's electric vehicles have an environmental advantage over cars with diesel or gasoline engines. This is even when taking into account battery recycling at the end and charging the vehicle over its entire lifetime with Germany's current electricity mix.

But where does the electricity come from?

Overall, that environmental advantage has also tended to grow in recent years and is now between 20% and 30%, according to Helms. Just a decade ago, similar studies put electric vehicles on par with efficient diesels.

But back in 2010, the share of green electricity in Germany was around 16%. By June of this year it was up to nearly 48%. That's one reason why the lead of electric cars grew a little year after year, despite the simultaneous efficiency gains in combustion engines.

Even among experts though there is often a dispute about the actual carbon footprint of electric cars. Just last week an aggressive exchange of blows was on display.

In an open letter to the EU, combustion engine experts claimed that the CO2 emissions created during the charging process of electric cars could be underestimated by a factor of at least two due to a newly discovered calculation error.

The letter also called to keep using vehicles with internal combustion engines in the future — but ones that run on bio or artificially produced fuels. Other scientists, who do not belong to the combustion engine fan club, responded promptly.

Accusations among researchers

The letter was branded, among other things, as "extremely embarrassing" and "a scientifically disguised lobbyist letter" that tried desperately to save the "piston engines."

The supposed calculation error was in reality a conscious decision and has been a methodological standard that has been in place for years.

Yet it is a strange time for such heated arguments among researchers. Many of the big players in the powerful automotive industry — above all Volkswagen — have long since set their course in the direction of electromobility.

Helms also considers electric cars to be the best solution in terms of the environment, if you absolutely need a car. "Overall, it would, of course, be better to avoid the car as much as possible and to use a bicycle or public transport," he said

When it comes to generating renewable electricity, we are at least on the right track and current electric vehicles use it in a particularly efficient manner. However, there are further challenges in the actual vehicle manufacturing process.

"Because sooner or later renewable energies have to be used in the mining, transport and processing of raw materials as well as in the further production process in order to achieve zero-emission mobility over the entire life cycle," said Helms. "Getting this complex value chain under one roof is a big challenge."

Another challenge in Germany is the new supply chain law, which makes German manufactures partly responsible for human rights and environmental protection at their suppliers.

This article was adapted from the original German.