Checkpoints might become a familiar sight next year on the streets of Stuttgart, but police won't be looking for drugs or weapons. They will be searching for illegal Euro 5 diesels. As odd as it sounds, randomly stopping cars would likely be the only way without enacting a new law for authorities to determine if a vehicle's exhaust was clean enough to enter the city. This traffic-snarling scenario could become a reality for drivers should local authorities be ordered by courts to finally uphold a 7-year-old clean air target from the European Union.
The diesel engine is at the forefront of the debate about potential driving bans. A discussion that has caused sales of diesel-powered cars to drop sharply in Germany, where politicians are considering joining France and the UK in banning all combustion engines starting in 2040.
Diesels burn up to 25 percent less fuel than gasoline engines, so they are crucial to helping automakers reduce overall fleet carbon emissions to 95 grams per kilometer by 2021 from 118.1g/km now. "Diesel clearly is needed to reach the midterm climate and CO2 targets," BMW Group CEO Harald Krueger told reporters at last month's Frankfurt auto show.
For diesels, the main problem is that they produce more smog-causing pollutants collectively called nitrogen oxides (NOx) than gasoline engines. If the diesels are to survive, however, carmakers know they must produce engines that are cleaner during real driving and not just on the test bench. That is why Krueger pointed out at Frankfurt that independent tests show his latest BMW 520d can also deliver low NOx emissions in a real-world setting and why he said: "I don't hold any stock in driving bans, sales bans or bans in general."
Krueger's position on bans doesn't change the fact that BMW's home city of Munich isn't far behind Stuttgart in pollution, leaving diesel drivers facing a similar dilemma. Twenty-eight areas in Germany regularly breach EU clean air limits when it comes to hazardous nitrogen dioxide (NO2), a major emission of diesel passenger cars. Dozens more high-pollution cities are found across the UK, France, Italy and Spain including all the major metropolitan centers led by London.