Slower is not always better for nature
![30 sign at road works](https://topgear.static-vds.nl/uploads/2020/10/bord-30-km--scaled.jpg)
In recent years we have slowed down more and more. First, the maximum speed was reduced from 130 to 100 km/h and in built-up areas from 50 to 30. There have already been studies that it is not necessarily safer, but now it also appears that it is not always more economical. Now we are certainly not in favor of tearing through residential areas, but a little more pace here and there is nice.
The French government commissioned Cerema (or Center d’études et d’expertise sur les risques, l’environnement, la mobilité et l’aménagement, if that’s easier for you) to study vehicle emissions at different speeds. What seems? Slower is not necessarily more economical.
30 km/h is less economical than 70
The researchers calculated the average emissions of the French fleet at different speeds. They also looked at the predicted composition of the vehicle fleet in 2030, 2040 and 2050. We will not bore you with all the details – for that you can the full investigation consult – but it is interesting to see the curve of the emissions. All graphs (CO2, nitrogen and particulate matter) show a U-shape.
The most economical only from 60 km/h
According to the data, cars currently emit the most emissions by far at low speeds. At 10 km/h, for example, the emission is 300 grams of CO2 per kilometre. At 30 km/h that is still 200. The most economical is the car with a speed between 60 and 90 km/h. After that, the line starts to rise again to 200 grams at 130 km/h. The fleet of 2050 would run just as inefficiently at 10 km/h as at 130 km/h (about 140 grams of CO2 per kilometre).
![](https://topgear.static-vds.nl/uploads/2021/08/grafiek-uitstoot.jpg)
Graphs of particulate matter and nitrogen show broadly the same trend. In modern cars, the U-shape of the graph is increasingly flattening, but it remains the case that cars run more economically at speed. In itself logical, because you have probably noticed that your engine runs a bit better (and more efficiently) if it is not at the bottom of the revs.
So, tearing through residential areas?
A lower maximum speed does not have the sole function of reducing emissions. In residential areas it is safer for everyone if you just drive slowly. In the Netherlands, however, the new standard maximum speed in built-up areas in the Netherlands is now 30 km/h. Where it benefits the safety of cyclists and pedestrians, that is of course a good thing. But roads without cycle paths or footpaths should therefore remain 50 or 60 km/h – that is so good for nature.
Through: Auto55