In the FDP party`s election program for the federal election in February 2025 the party addresses the question whether the speed limit would make German highways safer and save a lot of carbon dioxide. The party declares: „No, both is not right.” This factcheck focuses on the second part of that claim. Especially because the party commissioned an expert report on this matter. That expert report turned out to be misleading and therefore is mostly false.
The FDP’s position and the debate on speed limits
The FDP party is known for its liberal stance and for that reason it is often opposed to new prohibitions. The speed limit is seen as a significant restriction when it comes to driving on German highways.
For fifty years, this topic has been an ongoing debate in German politics. In the latest elections, the speed limit is once again a talking point. Primarily it was a question of road safety on highways, now it has increasingly become a matter of energy and climate policy.
Germany’s unique position in Europe
With approximately 13.000 kilometers, Germany currently has the fourth-longest highway network in the world, as stated by motor1.com, a German motorsports website. A speed limit of 130 km/h applies on just over half of Germany’s highways. Around 30 percent of the network has a permanent speed limit, while the remaining 20 percent is equipped with sign gantries that can display speed limits depending on traffic or weather conditions. According to a study by the German Economic Institute, around 80 percent of drivers already drive slower than 130 km/h on stretches without speed limits. Only less than 2 percent exceed 160 km/h.
In Europe, Germany has a unique position due to its lack of a general speed limit – therefore it is a frequently discussed topic not just nationally but also abroad. Other European countries have general speed limits, for example France with 130 km/h, Spain with 120 km/h or the Netherlands where the limit is 100 km/h during the day (6 a.m. to 7 p.m.) and 130 km/h at night.
Evidence from independent studies
To emphasize the significance of a speed limit on German highways, the Federal Environment Agency (UBA) conducted a research project in 2024 with the name “Liquid traffic for climate protection and air pollution control”. The goal was to determine the contribution that speed restrictions can make to reducing environmental pollution.
The study is based on floating car data, which is traffic data collected from vehicle GPS movements, for the entire German highway network and a nationwide traffic model. The higher CO₂ savings compared to previous studies are due to the more precise determination of vehicle consumption and the new consideration of changes in route choice and traffic demand. According to the authors, taking these factors into account provides a more realistic picture of the actual CO₂ savings from a speed limit. One of the most important results from the study is that a limit of 120 kilometers per hour would save around 6.7 million tons of carbon dioxide annually.
The FDP’s counterstudy and its shortcomings
The UBA study caused a lot of uproar in German politics. In response to the results of the UBA study, the FDP party commissioned an expert report in the year 2023.
The FDP criticizes the UBA study on the following points: its model makes unrealistic assumptions about driving behavior and traffic diversion. From the FDP’s perspective, the cost per ton of CO₂ avoided is also too high. The authors consider a general speed limit to be an inefficient climate protection measure.
Therefore the FDP´s report finds that the reduction effect of greenhouse gases with a speed limit of 120 km/h is only around 1.1 million tons of CO₂ per year – not 6.7 million tons as stated in the UBA study. This means a CO₂ avoidance cost of 390 euros per ton. This would be roughly five times the current price of emission certificates.
Alexander Eisenkopf and Andreas Knorr, the authors of the FDP-commissioned study, estimated the potential CO₂ reduction from a 120 km/h speed limit by multiplying three simplified factors: the share of autobahn traffic without speed limits (55%), the share of driving above 130 km/h (38%), and the estimated CO₂ reduction at 120 km/h (13.3%). This led to a calculated reduction of only 2.8%.
However, the Federal Environment Agency criticized this approach in a report in 2023 as methodologically flawed. The FDP study used emission factors that included heavy trucks, which are not relevant for evaluating car emissions. They also ignored that emissions differ by certain traffic situations – not just speed.
The UBA emphasized that emissions modeling must consider road type, traffic flow, and driving behavior, which their study does. As a result, the UBA estimates a significantly higher CO₂ savings potential, up to 6.7 million tons per year.
An independent assessment of the expert debate
The disagreement between the FDP study and the UBA reflects a broader expert debate over modeling assumptions and methodology. However, it is worth noting that the FDP study deliberately seeks a low estimate to emphasize economic counterarguments and to support their position in the election program. Also it is worth highlighting that several independent studies such as the study from the Federal Agency for Roads and Traffic or the study from Agora Energiewende shows that they expect a significantly higher savings potential than the 1.1 million tons of the FDP study.
Conclusion
The FDP party`s claim that a speed limit on German motorways would not save a significant amount of CO₂ is mostly false. Independent studies, such as the report by the Federal Environment Agency, estimate a potential saving of around 6.7 million tons of CO₂ per year with a speed limit of 120 km/h. The report commissioned by the FDP underestimates this value due to flawed methodology and assumptions like oversimplifying traffic patterns or including irrelevant vehicle types. While the exact CO₂ savings can differ depending on the model used, there is common agreement in independent research that the reduction would in fact be significant.
RESEARCH | ARTICLE © Johanna Sturm | Hochschule der Medien, Stuttgart, Germany
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