Diesel cars make up roughly a third of the car fleet in Germany | Mark Renders/Getty Images German politicians gather to avoid a clampdown on diesel cars They are shying away from confronting the country’s most powerful industry.

Angela Merkel, her rival for German chancellorship Martin Schulz and local politicians of all political stripes have one thing in common: They are desperate to avoid a ban on diesel cars in polluted German cities.

Any kind of restriction that threatens the country's largest industry ahead of national elections on September 24 amounts to “political suicide,” according to Timo Lochocki, a political scientist at the German Marshall Fund of the United States.

That's why Merkel meets Monday with state and city officials from the most polluted cities across Germany. They are gathering in Berlin to figure out a way to cut urban pollution without resorting to the nuclear option of preventing diesel-powered cars from driving into city centers.

“We have absolutely no interest in car bans,” said Janina Salden, a spokeswoman for the German local authority federation Deutscher Städte- und Gemeindebund, which will be represented at the meeting. It would “harm many individual users, by making their cars worthless,” she said.

Cities are under growing pressure from environmental groups. Air pollution limits of 40 micrograms of nitrogen oxide (NOx) per cubic meter of air were breached in 90 German cities last year, with Stuttgart and Munich being the dirtiest, according to the federal environment ministry.

NOx is an air pollutant produced by diesel engines and is the main ingredient of the smog choking cities across the Continent. The Dieselgate scandal, in which Volkswagen installed software to get its cars to cheat on emissions tests, focused public attention on the problem.

Now, more than 50 German cities face legal challenges from nongovernmental organizations — led by Deutsche Umwelthilfe and, in many cases, with support from activist lawyers ClientEarth — demanding they take additional steps to cut emissions, including restricting diesel cars. The environmental push has already had an impact after courts ordered several cities, including Munich and Stuttgart, to come up with more effective air quality plans and to consider diesel bans.

Because diesel cars make up roughly a third of the car fleet in Germany, "it's not that simple,” said Michael Münter, head of strategic planning and sustainable mobility in the mayor's office of Stuttgart, home to Mercedes-Benz and Porsche. Cities are looking at measures ranging from making mass transit more affordable to increasing the number of electric buses to cut down on pollution.

The car industry is one of the country’s main growth engines, employing hundreds of thousands of people and providing the biggest share of the country's exports.

Both Merkel and Schulz have said that diesel cars will be driving on German roads for years to come.

"The two major parties are heavily dependent on the auto industry, because it's the backbone of the German economy and because they are in part personally involved,” Lochocki said.

That's why there is almost no difference between Merkel and Schulz when it comes to the car industry.

“They don’t quite know how to handle this, and the safest bet is not to make a big issue about it,” Lochocki said.

Looking for answers

Cities, however, are increasingly unable to ignore the growing pressure. In addition to the lawsuits, there is a lurking threat from Brussels. The European Commission is taking notice of the government's reluctance to address the problem — launching several infringement cases against Germany for breaching EU air pollution rules.

In an effort to avoid car bans, and legal trouble, city governments are putting pressure on Berlin to consider measures they say would help clean up smog.

One is a so-called blue sticker scheme meant to differentiate between polluting and cleaner cars and make it easier to keep the dirtiest cars out of city centers while allowing newer and cleaner models in.

“Mayors say, 'Please give us the opportunity to have this blue sticker because otherwise the courts will sentence us with a diesel ban,'" Münter said.

Stuttgart Mayor Fritz Kuhn, a member of the pro-environment Green party, will press “prominently and very loudly for the introduction of the blue badge” at Monday's meeting, Münter said, adding that colleagues from Hamburg, Munich, and Düsseldorf would back the scheme, which needs federal approval.

“There is impatience over the federal government acting a little bit too slow and, especially on the blue badge, not reacting at all,” Münter said.

Mayors want to use Monday's meeting to push their concerns higher up Merkel's agenda. That includes financial support for cleaner transport systems and expanded public transport, cycling infrastructure and charging networks for electric vehicles.

One outcome from the meeting could be more money for local authorities. German paper Stuttgarter Zeitung reported Thursday that a €500 million joint fund from the car industry and the central government could be doubled.

“We cannot assume that municipalities, which are already under financial pressure, now single-handedly implement a transport transition,” Salden said.

After long trying to downplay the crisis within the German car sector, Merkel is now paying attention. She held a summit with the industry in early August, at which carmakers agreed to update vehicle software to ensure they pollute less and to finance a bonus for people exchanging older diesel models for cleaner cars.

Another meeting is planned for this fall.

“We want to step by step get to a point where driving bans are not necessary, but climate regulations are still being met,” Merkel told a press conference last week.

Victor Brechenmacher contributed reporting from Berlin.