On some parts of the autobahn, drivers are free to go as fast as they wish. On other parts, there are speed limits of 60 to 75 mph. Here a sign displays a speed limit of 120 km/h (75 mph) on the highway near Salzgitter, Germany. (Julian Stratenschulte/EPA)

BERLIN — For many in this car-crazy nation, the freedom to hurtle down the famed autobahn at 120 mph or more is an inalienable right.

Germany, one of the world’s top car producers, is alone among industrial countries in allowing drivers to decide for themselves how fast to race along the highway. So a proposal this month to impose a speed limit of 75 mph has set off an election-year battle that has some people questioning a basic tenet of German identity.

The traffic-cop-like suggestion from a top opposition leader challenged Germans to pick two popular obsessions — safety and sustainability — over another: a seemingly primal need to use their 500-horsepower engines to catapult themselves across their country’s gently rolling countryside.

On speed limits, “the rest of the world has been doing it for a long time,” Sigmar Gabriel, chairman of the Social Democratic Party, told the Rheinische Post, adding that Germans should drive slower for safety. Traffic deaths have been dropping for years in Germany, but Gabriel said they would drop faster if there were a speed limit.

His proposal, which revived a decades-old discussion in Germany, was quickly disowned by other senior members of his party, although other Social Democrats and members of the Green Party quickly lined up in support. Last week, lawmakers debated the speed limit in Parliament — under a dome from which one can see the rotating logo of German car giant Mercedes-Benz dominating the skyline of western Berlin. They took no action, nor is any expected before September parliamentary elections.

Road fatalities in Germany

On 60 percent of Germany’s autobahn, drivers are free to go as fast as they wish, and German-made BMWs and Mercedeses frequently shoot down the left lane at 120 mph. Elsewhere on the highways, usually in areas where traffic is heavier or near cities, there are speed limits of roughly 60 to 75 mph.

Speed limit advocates have appealed to the one thing that many Germans like almost as much as their cars — the environment — and that, in the end, may be what pushes the country to act. Driving more slowly reduces emissions and uses less gas, and at a time when Germany is moving ahead with plans to dramatically reduce greenhouse gas emissions, rocket-fast Porsches strike some here as a little hypocritical.

Opinion polls show Germans split over the idea, but the issue is so sensitive that it is unlikely to be acted upon until after the September balloting. Chancellor Angela Merkel opposes speed limits, although she is never seen behind the wheel, unlike her Audi-loving predecessor, Gerhard Schröder. Merkel’s Christian Democratic Union has a comfortable lead in the polls.

“There won’t be a general speed limit on Germany’s highways under my rule,” Transportation Minister Peter Ramsauer said in a statement. Ramsauer is an amateur pianist who in 2011 released a CD called “Adagio in the Auto,” on which he and other musicians played slow classical compositions intended to calm drivers as they navigated Germany’s 7,936 miles of autobahn.

Speed limits are deeply tied to Germany’s postwar identity. Adolf Hitler built up the country’s highway network, but the Nazis instituted a nationwide speed limit of 50 mph to conserve resources after World War II started in 1939. By 1953, with the country’s postwar industrial boom underway, speed limits for cars were eliminated. They were later added in cities and on some stretches of highway.

In a country so devoted to safety and sustainability that it is phasing out nuclear power in large part because of fears stemming from the 2011 Fukushima Daiichi nuclear accident in Japan, Germany’s strict adherence to fast driving seems incongruous.

“People think they have more freedom” without the speed limits, said Ferdinand Dudenhöffer, the director of the Center Automotive Research at the University of Duisburg-Essen, who added that he takes his BMW up to 115 mph if the road is clear but usually drives at 75. “You could compare it a little bit with the U.S. position of having guns.”

Dudenhöffer used to work for Porsche, where American buyers would occasionally come to pick up their cars and sample German roads, he said.

“But they would then just drive it at 60 miles an hour,” he said. “They weren’t used to driving 250 kilometers per hour,” or 150 mph, he said.

Germany’s roads, constructed to some of the strictest safety standards in the world, rank firmly in the middle of industrialized countries in terms of traffic deaths. For every billion miles driven on German roads, nine people were killed in accidents in 2011, according to figures to be released this week by the International Transport Forum of the Organization for Economic Cooperation and Development. In the United States, 10.9 people died for every billion miles driven, while in Britain, 6.3 people were killed.

Britain’s speed limit is 70 mph. U.S. speed limits are set by the states. The highest, 85 mph, is found in some parts of Texas. Most highways range between 65 and 75 mph, though in urban areas the limits are often lower.

German opponents of speed limits say drivers are smart enough not to go faster than is safe.

“We have a lot of motorway sections that have bottlenecks and congestion, so people are quite happy if they can drive a little bit faster on tracks where it’s possible,” said Jürgen Berlitz, a traffic expert at ADAC, a German drivers association.

But some say that argument is absurd given that 387 people died in accidents on the autobahn last year.

“If in Germany within one year, two fully booked airliners with 400 people crashed, what a debate about air traffic security we would have,” Stephan Kuehn, traffic policy spokesman for the Green Party, said in a parliamentary debate last week. “Every road traffic death and injury is one too many.”