By Jorn Madslien

Business reporter, BBC News, Detroit



Diesel fumes from large trucks have spooked American drivers

Overpowering diesel fumes fill the cabin of the double-cab pick-up as it lines up behind hundreds of idling trucks, stuck queuing at North America's busiest border crossing.

Ambassador Bridge, which links Canada and the US in a graceful stretch across the Detroit river, may be beautiful.

But it stinks.

For many Americans, slow-moving queues such as this one are seen as a necessary evil.

The 18-wheeler trucks that cross the bridge transport more than a quarter of all trade between the two nations by volume, adding tens of thousands of jobs and some $10bn to $15bn (£5.1bn to £7.7bn) to economic output, according to some estimates.

But they also belch out tonnes of diesel, which has been widely blamed for a range of ailments ranging from bronchitis to asthma to lung cancer.

Reluctant consumers

At a filling station a couple of miles down river from the Ambassador Bridge, a virtual line is drawn between the diesel pumps in the truckers' area and the area where drivers of cars and light trucks fill their tanks.

Trucks in one area, cars in the other

These days, most urban filling station offer diesel in both areas - though there may be just one diesel pump - yet the filling station's layout often remains as a potent symbol of a line that many Americans are loath to cross.

In a country where the "filthy fuel" is generally reviled, most would not even consider buying a diesel-powered family vehicle.

And yet, in spite of such extreme distrust in - or disgust with - diesel, European auto makers are preparing a massive onslaught of diesel-powered models that they say will help cut fuel bills and reduce greenhouse gas emissions by up to 25%.

This year, for the first time, diesel-powered cars that meet the emissions regulations in all 50 states will arrive in the US, says Stefan Krause, BMW's executive director in charge of sales and marketing, in an interview with BBC News.

"If you point out the environmental friendliness of these cars and if you point out that it's more cost effective than petrol, then high performance diesels will be accepted," he predicts.

Dieter Zetsche, chief executive of Daimler, which owns Mercedes-Benz, agrees.

"We are very bullish about the prospects for diesel in this country," he tells BBC News.

Clean diesel

The Germans are leading the charge

Angus MacKenzie, editor-in-chief, Motortrend

Much of the science is on the side of modern diesel, which has a sulphur content limited to 15 parts per million (ppm), compared with up to 500 ppm found in the diesel of yesteryear.

Consequently, a growing number of industry observers agree with the claims made by manufacturers of diesel-powered cars: "Diesels can produce enormous improvements in the short-term," according to Paul Ingrassia, author of Comeback: The Fall and Rise of the American Automobile Industry.

The emergence of so-called "clean diesel" has taken Europe by storm and now outsells petrol pretty much across the board.

Diesel now accounts for more than half of all new cars sold in Europe, and only a quarter of luxury car buyers in Europe choose petrol engines, though this is largely because of tax rules that favour diesel.

In the US, meanwhile, diesel has yet to rise above a single-digit market share in any segment, though there are early signs that wealthy drivers, who are more likely to choose cars made by non-US manufacturers, are keen to embrace the fuel.

"Where we offer diesel it accounts for 20% of sales," observes Daimler's Mr Zetsche.

"Mercedes is now going for more and more diesel in the US," he adds, and so are its main European rivals, Audi and BMW.

"The Germans are leading the charge," observes Angus MacKenzie, editor-in-chief of Motortrend.

Big and powerful

In Europe, carmakers are offering a broad range of diesel-powered vehicles that have been specially designed to meet the continent's much stricter environmental regulations.

But do not expect the same model ranges to go on sale in the States.

All the German manufacturers aim to woo US drivers with diesel-powered muscle-cars in a carefully thought-out effort to convince Americans that a switch to diesel will not involve sacrificing performance.

Diesel is not slow, honest, the Germans say

"One of the perceptions is that they are slow and weak cars," says Mr Krause.

"We don't think the consumer is interested in downsizing, in giving up something, especially not the American customer."

So to reinforce the performance aspects of diesel cars, at last month's motor show in Detroit, Audi showed its R8 super-car concept with a 500 horse power V12 6.0 litre turbo diesel engine.

Audi will also introduce diesel to its large A8 executive car this year and Mercedes is rolling out its Bluetec range.

BMW, meanwhile, will bring diesel to the US market this year with its 335d model, which packs 265 horse power into a 3-litre diesel engine that it says will deliver 23 miles per gallon (mpg) in the city and 33 mpg on the motorway.

Diesel discounts

BMW is confident many American drivers will switch to diesel

This focus on powerful diesels also makes them more expensive, not least since their modern emissions systems are also forcing up costs.

The total price premium for modern diesels can easily reach $3,000 to $4,000 per car, which will be a bridge too far for most Americans, according to the indigenous automotive giant General Motors.

Mercedes' marketing people seem to agree, so when it launched its E320 Bluetec model in California last autumn it came with a lease agreement at a price comparable with its E350 petrol engine.

"The margins on diesel are somewhat lower", acknowledges Mr Zetsche.

"We did not want to burden it with a big price."

It is a strategy that BMW's Mr Krause is loath to copy.

"We don't believe we'll have to give price concessions to be successful with diesels in this market," he declares.

"These guys have good diesels for farm equipment. We're developing high performance diesels for roads."