“I’m just as angry about the fraud as you,” Ms. Merkel said in an interview with the magazine Der Spiegel published Sept. 2, illustrating her newly critical attitude toward the industry. But she has not completely abandoned the industry. Ms. Merkel is scheduled to speak at the opening ceremony for the International Motor Show in Frankfurt on Thursday.
For decades, the German government has been a crucial ally for carmakers, operating as a de facto lobbyist for the industry.
With the active support of officials, automakers used their political clout in Brussels to block stricter emissions regulations and to promote subsidies for diesel. German leaders, including Ms. Merkel and her predecessor, argued against tough emissions rules and pushed for better terms for the country’s carmakers abroad.
Most recently, Germany led a group of auto-producing countries in weakening European emissions testing procedures that were designed to prevent the kind of deception committed by Volkswagen. New cars must pass road tests. Previously, they had to pass only laboratory exams, which Volkswagen and other carmakers were able to game. But, at German insistence, cars can emit double the legal limit of nitrogen oxides and still be approved.
German political leaders and automakers have worked together to promote diesel technology since the 1990s. Ms. Merkel’s predecessor, Gerhard Schröder, was proud to be known as the “auto chancellor.”
Germany has taxed diesel fuel at a lower rate than gasoline since the 1980s, originally to make truck transport, which is predominantly diesel, less expensive. The goal, according to a 2011 study by Transport and Environment, an advocacy group in Brussels, was to lower costs to help German manufacturers compete internationally.
In the 1990s, the auto industry preserved the subsidies by convincing politicians that diesels were better for the environment than gasoline engines, a dubious claim given the other pollutants that diesel spews. For years, environmentalists’ calls to raise diesel taxes have met opposition from the country’s largest political parties, including Ms. Merkel’s Christian Democrats.
Those tax breaks have ensured that diesel is significantly cheaper at the pump, leading to a steady rise in the popularity of diesel-powered cars. Until recently, they outsold their gasoline-powered counterparts around Europe.
German carmakers and politicians engaged in a similar battle in Brussels, fighting for years to bat away tougher emissions rules. In 2013, Germany used its clout as the European Union’s largest economy to intervene when the bloc’s executive arm wanted to tighten limits on carbon dioxide emissions.
Matthias Wissmann, head of the German Association of the Automotive Industry and a former transportation minister, wrote a letter to Ms. Merkel, warning that the new standards would hurt sales of German luxury cars. In that letter, he addressed Ms. Merkel as “du,” the informal German word for “you” normally used only between close friends.
Ms. Merkel then personally called Prime Minister Enda Kenny of Ireland, who held the rotating presidency of the European Council, and persuaded him to delay a decision. The standards were eventually watered down.
German leaders campaigned for carmakers farther afield, too. On a trip to California in 2010, Ms. Merkel complained about the state’s strict limits on nitrogen oxides during a meeting with Gov. Arnold Schwarzenegger.
“She said, ‘Your nitrogen oxide limits are too strict, and that is hurting our German diesels,’” Mary Nichols, the chairwoman of the California Air Resources Board and an attendee at the meeting, said in testimony to the German Parliament in March. “She was there, it seemed, as spokeswoman for the auto industry.”
The bond between politicians and automakers persisted even after the Volkswagen scandal erupted.
Stephan Weil, prime minister of Lower Saxony, home of Volkswagen, conceded in August that he had allowed company lobbyists to vet a 2015 speech about the emissions deception. The state of Lower Saxony owns a 20 percent stake in Volkswagen, and Mr. Weil sits on the carmaker’s supervisory board.
Mr. Weil, a member of the Social Democrats, denied making significant changes to the speech after it was shown to Volkswagen. Thomas Steg, head of government relations for the carmaker, said Volkswagen looked only for factual errors.
The case, first reported by the newspaper Bild am Sonntag, helped spur a turnaround in public perceptions of diesel, once a point of national pride.
The diesel engine, like the automobile, was a German invention, and the country’s carmakers leveraged their know-how to achieve dominance in the European luxury car market. The auto industry, including suppliers, currently employs about 2 percent of the German work force, according to Commerzbank.
Against that backdrop, deep political ties were forged.
German carmakers have often recruited government insiders to represent their interests. Mr. Steg of Volkswagen was once a spokesman for Ms. Merkel. Eckart von Klaeden, responsible for Daimler’s relations with governments worldwide, served under her as a junior minister.
All of the country’s main parties, even the environmentalist Greens, have long histories of amiable relations with the auto industry. Joschka Fischer, a former foreign minister who for many years was standard-bearer for the Greens, now works as a consultant to BMW, though the carmaker says he does not do any lobbying.
While money plays a much smaller role in election campaigns in Germany than in the United States, the auto companies nevertheless make their presence known. Daimler, for example, contributed 100,000 euros, or about $120,000, each to Ms. Merkel’s party and to the Social Democrats, according to documents filed at the German Parliament. The carmakers also help to finance party events and loan cars for free to elected officials, activities that they are not required to disclose.
BMW said in a statement that it had tightened its rules on interactions with politicians, ensuring, for example, that parties report the use of vehicles as a financial contribution. Daimler did not respond to a request for comment.
Mr. Steg, the Volkswagen lobbyist and former aide to Ms. Merkel, said a close relationship between carmakers and politicians was of common interest. Others argue that lobbying helps auto executives understand the workings of government, and public officials understand the car business.
“The government has its own positions,” said Mr. Wissmann, the head of the auto industry association. “It has not simply followed the positions of the auto industry blindly.”
Since the end of World War II, Mr. Steg said, “politicians have always had a huge interest in the well-being of the industry and the creation of jobs.”
As the scandal’s focus expanded, German officials have found themselves on the defensive.
The government’s own study last year showed that virtually all makers of diesel cars had flouted emissions limits, but Ms. Merkel’s ministers did not impose penalties. Germany now faces a lawsuit by the European Commission over failures to enforce the bloc’s clean air rules.
The German government has also rejected calls to require carmakers to install better emissions equipment in older diesel vehicles. Britain and France have promised to ban internal combustion engines starting in 2040, but Germany has not done the same.
“They take the line of industry,” said Julia Poliscanova, manager of clean vehicles and air quality at Transport and Environment, an advocacy group in Brussels, “instead of citizens and public health.”