MUNICH – BMW AG reveals its first major diesel push in the U.S. and Canada will begin with a 3.0L inline 6 cyl. with variable twin-turbo technology.

The German auto maker, which has offered a diesel engine for 24 years in Europe and now counts seven such mills in its lineup, first announced in 2006 plans to bring one of the award-winning powertrains to the U.S.

During a recent competence exercise here, BMW identifies that powertrain as the 3.0L twin turbo, a mill that accounts for 1% of 3-Series sedan sales and 7% of 3-Series coupe deliveries in Europe. Its greatest penetration is in the X3 cross/utility vehicle, with 8% of all vehicles fitted with the engine, BMW says. On the 5-Series, it appears in 5% of all sedans and 7% of all touring models sold in Europe.

The auto maker remains mum on pricing and which model, or models, may receive the engine in the U.S. At the competence exercise, BMW offers the engine for testing in a 335d coupe, sedan and touring model; 535d sedan and touring model; and 635d coupe.

In the U.S., the auto maker’s most popular mill is the similarly sized 3.0L DOHC I-6, a Ward’s 10 Best Engines award winner the past two years. The 24-valve gasoline engine appeared in 91% of BMW vehicles sold in the U.S. in 2006, including 87.5% of 3-Series models, according to Ward’s data. The mill also was fitted in a majority of X5 CUVs, assembled in Spartanburg, S.C.

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Satch Carlson, editor of Roundel, the official magazine of the BMW Car Club of America, says the 335d and 535d would make the most sense in the U.S.

“Both of these models are absolute rockets, especially when accelerating from freeway speeds to Autobahn speeds,” says Carlson, who has tested the cars extensively.

The twin-turbo 335d in Europe makes 286 hp and 427 lb-ft. (578 Nm) of torque.

“That makes it a performance engine in the American tradition of the stop-light Grand Prix,” Carlson says.

The same car also achieves a combined cycle of 35 mpg (6.7 L/100 km). By comparison, the turbocharged ’08 335i for U.S. delivery gets a combined cycle of 20 mpg (11.7 L/100 km) and delivers 300 hp and 300 lb.-ft. (406 Nm) of torque.

Until earlier this year, BMW downplayed the prospect of bringing a diesel engine to the U.S., although oil burners account for 67% of its sales in Europe and 40% of its engine installations worldwide. BMW has long maintained it would be too difficult to fully recover the cost of diesel engines and their accompanying complex exhaust treatment systems.

It even passed on a partnership with fellow German auto makers DaimlerChrysler AG, Audi AG and U.S.-market leader Volkswagen AG to jointly develop and market a diesel engine that would meet emissions regulations nationwide and likely ease those cost pressures.

Those auto makers now are marketing diesel technology under the Bluetec name, which uses urea injection to meet most states’ emissions standards.

BMW also has said it feared offering a diesel alternative to its lineup of performance-oriented gasoline engines would make for few conquest sales.

The auto maker undoubtedly recalls the industry’s last diesel push with passenger cars in the U.S. some 30 years ago, an experiment that failed miserably in a black, smelly cloud of exhaust. U.S. consumers have resisted diesels ever since.

But times have changed and so has the diesel, says Fritz Steinparzer, director-diesel engine development, BMW.

“We think, with the diesel technology we have now, we can change that perception,” Steinparzer says. “Diesels are a good opportunity against hybrids.”

The key element of BMW’s diesel technology is the exhaust system’s particulate trap, which brings the engine into compliance with strict U.S. Tier II bin 5 emissions standards. The trap also is maintenance free, which BMW considers a first. In addition, the auto maker says the trap does not diminish engine power or increase fuel consumption – a bugaboo of many such solutions.

Much like its competitors at Mercedes and Volkswagen, BMW’s technology additionally relies heavily on a sophisticated aftertreatment process, which injects small amounts of diluted, ammonia-based urea solution into the exhaust stream to convert toxic oxides of nitrogen emissions into a harmless mix of nitrogen and water.

Steinparzer says the system eliminates more than 99% of harmful emissions.

“We’re really close to zero (emissions),” Steinparzer says, adding that he thinks BMW will take a leadership role in performance diesel offerings in the U.S. next year. “There is no other manufacturer that can offer this technology at this time.”

Another key element of the engine is its twin turbochargers. BMW placed a larger, principle blower underneath the engine and a smaller, standby turbo on top. From a stop, or at slower speeds, the engine uses both. But at higher speeds, it bypasses the smaller turbo to rely solely on the bigger one.

“It is the most efficient turbocharger there is today,” Steinparzer says.

Other features of the engine include a common-rail fuel system with piezoelectric injectors rated at 29,000 psi (2,000 bar) and capable of up to five injection events per combustion stroke. A newly developed, high-pressure pump feeds the injectors. An aluminum crankcase helps trim overall weight of the engine.

But whether U.S. consumers embrace the engine remains to be seen, especially if it comes with the $2,000-$3,000 markup analysts expect.

Carlson says this diesel will impress fuel-conscious consumers cross-shopping in the segment and satisfy current BMW owners that have been clamoring for the auto maker to bring its diesels stateside for their low-end torque performance quotient.

“It isn’t noisy and it doesn’t stink like a Ford pickup,” he says. “You can hear a slightly different sound from the engine at idle, if you’re outside the car. But inside, there’s just a reassuring bass rumble on acceleration. It feels and sounds something like a big-block Chevy when you put your foot down.”

Diesel engines currently account for 3% of the U.S. market, but by 2015 that number will jump to 12%, according to J.D. Power and Associates.

“We see the market growing pretty quickly,” says Michael Omotoso, senior manager-global powertrain forecasting for J.D. Power.

Omotoso says European and Asian manufacturers will make a push with diesels in their passenger cars, while General Motors Corp, Ford Motor Co. and Chrysler LLC will bring diesels into their light trucks.

Omotoso likes BMW’s chances against Mercedes, whose 3.0L engine does not currently compete on performance or meet 50-state emissions requirements. Audi has delayed its first diesel, a variant for its Q7 CUV, until 2010.

“It will do well,” he says of BMW’s diesel application. “It will be interesting to see whether they market it as a performance vehicle, on its fuel economy, or a little of both. People who drive BMWs normally can afford gasoline at $3 or even $4 a gallon.”

BMW won’t elaborate on its marketing plan for models with the engine, saying only that the effort would be on par with what it would do for any other new-vehicle launch. Carlson says a test drive is all it will take.

“It’s definitely not your father’s diesel,” he says. “Your hot-rodding Uncle Max, on the other hand, (is) gonna love it.”

jamend@wardsauto.com