In the future, thirteen figures on a yellow-orange notice board will show drivers what they could have saved. From October, larger filling stations will have to present their customers with a so-called energy cost comparison. On it: the costs for 100 kilometers with seven different energy sources - from electricity to hydrogen to premium gasoline - and for two vehicle sizes. Only for hydrogen in smaller vehicles a value is missing for lack of data. Why does the poster exist, what can it do - and what not?

Why does the placard exist?

It implements a European directive. Its purpose is "to support consumers' future purchasing decisions when choosing a passenger car," as the text of the law puts it. The idea behind it: Consumers should be able to easily compare what energy costs them for 100 kilometers with different forms of drive.In principle, the ADAC also thinks this makes sense in order to create transparency and "also to influence the purchase decision to a certain extent. The German Association of Energy and Water Industries (BDEW) also welcomes the labeling: "The comparison makes it clear that for many drivers, electromobility is not only a climate-friendly alternative, but also a financially attractive one," it says.

What does the poster show?

The current poster - which is to be updated quarterly and can be downloaded from the Ministry of Economics - shows, for example, that a mid-size or luxury car running on premium gasoline costs 11.42 euros in fuel or energy per 100 kilometers. With Super E10 it would be 11.00 euros, with diesel 7.48, with a Stromer 4.84. Natural gas H would strike with 6.39 euros to the impact, autogas with 4.96 and hydrogen with 7,60.

How are these values arrived at?

For each drive type in each of the two vehicle categories, the three best-selling vehicles and their official consumption according to the current WLTP driving cycle are used. This gives an average consumption per 100 kilometers. Together with the price for the respective energy source, this then results in a cost per 100 kilometers. For the price, the ministry uses the average value of the second quarter. However, these figures are not given on the poster.

How accurate are the figures?

Even if the values are calculated and stated to the cent, they can only be rough comparative values for several reasons. For one thing, the consumer who reads the poster when refueling probably drives a different car with different fuel consumption. His driving style also makes a big difference here.

In addition, according to the Federal Ministry of Economics, the average prices for the second quarter are currently used for the calculation. Since then, diesel, for example, has become around 11 cents per liter more expensive, according to figures from the ADAC.And finally, as the name suggests, it is only a comparison of energy costs. Other car-related costs such as purchase, repairs, insurance and tax are naturally left out of the equation - although they usually significantly exceed the energy costs item.

The special case of electric cars

The calculation is particularly susceptible to distortion in the case of electric cars, of all things, which according to the comparison are the cheapest to drive. "There is no information that the average household electricity price is used as a basis for e-cars," criticizes the petroleum industry association MWV. "Public and above all fast charging is usually more expensive, and that reduces the price difference to the gasoline-powered car considerably."

According to the energy industry association BDEW, a typical household electricity tariff is just over 30 cents per kilowatt hour. At public charging stations, however, it is more like 39 to 45 cents and at fast charging stations even 49 to 79 cents. Behind this are costs for infrastructure, operation, maintenance, land use and payment processing, among others. But these prices also have to be taken into account so that the information on the poster "can be reconciled with personal experience," BDEW demands.

The Ministry of Economics justifies the use of the household electricity tariff, among other things, with the fact that more than 80 percent of charging processes take place at home. In the medium term, however, the costs for charging on the road are also to be included in the calculation.

Where does the billboard have to hang?

Service stations with seven multiple pumps and more must hang it or present it on a screen. According to an estimate by the ZTG service station association, however, this only affects about 1,500 of the 14,500 service stations in Germany. That's "the only good thing" about the new regulation, says ZTG managing director Jürgen Ziegner, who thinks the poster is "as superfluous as a goiter." "After all, it's of little use to me if I'm on the road and have to refuel, and then find out how much I would have paid for electricity at home," he criticizes.

Image by Anton Porsche