When German politician Sigmar Gabriel suggested a speed limit on all stretches of the autobahn, there was a collective drawing-in of breath and raising of eyebrows. His party was perceived to have skidded on the slippery road to September's general election.

Why, many wondered, would a politician trying to win votes suddenly come up with a proposal so clearly doomed to lose them?

He might have suggested banning sausages for all the support he got, even from within the Social Democrat Party (SPD) - and he's its chairman.

It was, after all, a former chancellor from the SPD, Gerhard Schroeder, who described the land of BMWs and Porsches as an Autofahrernation - a nation of drivers.

So the proposal to put the brakes on in Germany went down like a flat tyre in the fast lane.

As a commentator in Bild put it: "With his go-it-alone suggestion of a 120km/h speed limit on motorways, Gabriel has confirmed an important judgment on himself: every day, he's good for a newspaper story and some days for two!"

Germans seem to regard it as a basic human right to get into their BMWs (or Mercs or Audis or Porsches) and scorch down the autobahn at warp speed.

Motorway speed limits around the world United Arab Emirates: 120km/h (75mph)

120km/h (75mph) USA: varies between states - 104-136km/h (65-85mph)

varies between states - 104-136km/h (65-85mph) Sweden: 120 km/h (75mph)

120 km/h (75mph) China: 120km/h (75mph)

120km/h (75mph) New Zealand: 100 km/h (62.5mph) In pictures: Hitler's autobahn dream

You can have your own foot flat to the floor only to be passed by a car which disappears in a blur of speed and go-faster machismo.

Others in the top echelon of the SPD were not amused, particularly as the party has been suffering in the polls against Chancellor Merkel's Christian Democratic party with the election just over three months away.

Peer Steinbruck, the SPD's candidate for chancellor and the other half of the centre-left party's leadership, said: "I do not think it's sensible to activate and ignite this debate. The issue is not in our programme for which I am answerable."

Bild's headline, by the way, was "Steinbrück pfeift Gabriel zurück" (Steinbruck whistles Gabriel back).

Sigmar Gabriel's argument was that studies show that speed limits decrease serious injuries and deaths from road accidents - as the rest of the world has long accepted.

Image caption Nein danke?

And it should be said that some stretches of autobahn - like junctions, areas of construction and accident black-spots - do have speed limits. In some built-up areas, there's a speed limit to keep noise down. The authorities have the power to impose restrictions where necessary but it is true there is no general restriction.

The speed limit debate According to the European Transport Safety Council (ETSC) studies show that the higher the speed of vehicles, the more likely they are to crash and the more severe any crash is likely to be

A 1% reduction in speed, leads to a 2% reduction in accidents causing injury, a 3% reduction in serious injury accidents and a 4% reduction in deaths, the ETSC says

Figures from 2006 show Germany in eighth place for motorway deaths per distance travelled, behind Switzerland, Denmark, the Netherlands, the UK, Sweden, France and Ireland ETSC autobahn speed limit factsheet

On the best estimate, about an eighth of the whole network of 13,000km (8,000 miles) has no speed limit and about a third has a permanent limit, with the bit between coming and going according to need.

What's it like pushing a car to its limits on an autobahn without limits? Three years ago, Automobile magazine did a road test on the A95 between Munich and Garmisch in southern Germany.

"We're in a 480-horse-power Porsche 911 Turbo cabrio, pedal to the metal in fifth - make that sixth - gear," wrote the reporter.

"At this speed, you need four eyes: one for the road directly in front of the car, one to scan the horizon for slower vehicles, one for the mirrors, and one for the instruments. The speedo shows 297km/h... 301...306... 311... 314... 314... 314... That's 195mph.

"On the return run, we'll briefly hit 200mph on the short downhill section near Murnau. This is white-knuckle, eye-wateringly fast. Even though your concentration is sharply focused, a clear picture stabilises for only fractions of a second."

There is another view. Greens in Germany think that speed limits would significantly reduce CO2 emissions (and they agreed with Sigmar Gabriel when he made his pronouncement).

Motoring organisations are more sceptical, although there is a group called the Verkehrsclub Deutschland for people who like to think of the environment (it advises on the right tyres to buy, or speed to drive to minimise emissions).

Kraftwerk - Autobahn There is a established tradition in rock music of writing about roads (Route 66, 2-4-6-8 Motorway), but nothing quite matches the 1974 LP Autobahn by the German electronic band Kraftwerk. The 22-minute title track pays tribute to Germany's roads. As Band member Wolfgang Flur explains: "We used to listen to the sound of driving, the wind, passing cars and lorries, the rain, every moment the sounds around you are changing, and the idea was to rebuild those sounds on the synth." BBC Music: Review of Kraftwerk - Autobahn

It says that little empirical research has been done recently, but there was a study in 1996 which showed that a speed limit of 120km/h (75mph) on autobahns (assuming it was observed by 80% of drivers) would reduce CO2 emissions from cars by about 10%, and one of 100km/h (62.5mph) would cut them by nearly 20%.

But there's obviously a wider argument to be had in a land of big car companies. Baden-Wuerttemberg, for example, is a state with a Green government but it is also the home of Porsche and Daimler (which includes Mercedes).

When Winfried Kretschmann became the state's premier, he said he favoured tougher speed limits to lower casualties and to lower emissions. "Gas guzzling luxury limousines are not the future," he told Wirtschaftswoche magazine.

This was not a tone to reassure the two big employers in his patch. Meetings were held. One was between Mr Kretschmann and Porsche chief executive, Matthias Mueller.

"This first exchange is a good start for an intense and above all constructive dialogue with the prime minister and his government," said chief executive Mueller, afterwards. "I am confident that with the necessary understanding for each other we can further strengthen the automotive state of Baden-Wuerttemberg."

This debate over speed limits has been going on for more than 100 years.

As the Allgemeine Automobil (General Motoring) magazine put it in 1906: "It's understood that excessive speeding is to be disapproved of - but a ban would be clumsy. A maximum speed for the open road is hardly workable."

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