How about a speed limit on the Autobahn?

Could Germans’ cherished right to drive as fast as they like on the Autobahn soon be outlawed? With the country’s center-left Social Democrats now leading the polls ahead of this month’s federal election, we shouldn’t rule it out: If voted in, they promise to limit motorway speeds to a maximum of 130 km per hour (81 miles per hour). Possible coalition partners, the Greens and Left party, also want a highway speed cap.
For libertarians and petrol-heads, not to mention the German engineers who spent decades building ever more powerful combustion engines, this would be hugely disappointing.
Motorway speed limits can lower fuel consumption and thereby cut pollution, including planet-heating emissions. This doesn’t just apply to road users. The shipping industry has been able to improve emissions just by sailing more slowly. Meanwhile, the European Union hopes higher aviation fuel taxes will encourage us to ditch planes for slower, greener trains. Although slower travel is no panacea, it does offer a quick environmental win, whereas full adoption of clean technology will take years.
To encourage the switch away from fossil fuels, governments should consider forcing polluting vehicles to slow down more, and cut cleaner vehicles some slack on speed.
It may not be a popular message, but we’ve known for decades that slowing down can reduce pollution. When cars go above a certain speed — roughly 55 mph depending on the vehicle type — fuel economy drops, in part due to increasing air resistance.
The US introduced a 55 mph freeway speed limit in the 1970s when oil prices surged, though the act was repealed two decades later. More recently, the Netherlands switched to a 100 kph (62 mph) daytime motorway speed limit to help cut nitrogen oxide emissions, while England lowered the speed limit from 70 mph to 60 mph on several motorways for similar air quality reasons.
A 130 kph Autobann speed limit would lower greenhouse gas emissions by 1.9 million tons annually, according to the German Environment Agency. That’s barely 1% of Germany’s overall transport emissions, but nearly 5% of the total produced by cars and light commercial vehicles on highways, it estimates. A 120 kph speed limit would remove even more.
The benefits of slowing down are significant in shipping due to the non-linear relationship between a vessel’s speed and fuel consumption. A 10% speed reduction results in 27% less energy use (or 19% after accounting for the additional time to complete the voyage).
Pioneered more than a decade ago by AP Moller-Maersk A/S, the world’s largest container shipping line, in response to soaring bunker fuel prices and overcapacity, the so-called “slow-steaming” approach is still widely used across the industry, even though freight rates are much higher.
Slower speeds are estimated to have lowered the emissions intensity of container shipping by 35% between 2007 and 2016.

—Bloomberg