SEOUL – GM Daewoo Auto & Technology Co. is converting its entire vehicle lineup to diesel applications by 2010.

“Our plan is to install diesel engines in all lines of passenger cars,” says Park Pyongwan, managing director of the 500-engineer strong GMDAT Powertrain Operation at the auto maker’s Bupyeong complex.

“Our current targets depend upon the vehicles, but we will be ready in 2009 and roll them out from the latter part of 2009 through the latter part of 2010,” he says in an interview with Ward’s.

GMDAT plans to do the job using two diesel engines.

The first is a 2.0L 4-cyl. mill produced at the auto maker’s dedicated diesel-engine plant in Gunsan, 150 miles (241 km) south of Seoul.

The TCDi ( turbo common-rail direct-injection) version became available last month to power the ubiquitous Lacetti sedan, hatchback and sport wagon.

The Lacetti is GMDAT’s primary export car line, accounting for 40% of international sales. It’s marketed as the Suzuki Forenza in the U.S., Chevrolet Optra in Europe, Chevrolet Lacetti in Australia and the Daewoo Nubira in other foreign markets.

The 2.0L TCDi generates 119 hp at 3,800 rpm and 207 lb.-ft. (280 Nm) of torque at 2,000 rpm.

A more powerful VCDi (variable turbo common-rail diesel-injection) variant of the same engine was made available on the Tosca premium sedan last November, as well as on the new Winstorm/Captiva cross/utility vehicle. The sedan and CUV also are exported overseas.

The VCDi develops 148 hp at 4,000 rpm with a maximum 236 lb.-ft. (320 Nm) of torque at 2,000 rpm.

Park declines to provide specs on the second engine, although he does confirm it has a considerably smaller displacement, fully meets Euro 5 requirements and is being refined to meet California emissions standards.

GMDAT is working jointly on the smaller diesel mill with GM Powertrain Europe (GMPE) and the program is “progressing nicely,” Park says. GMPE is General Motors Corp.’s second-largest powertrain development center behind the U.S. It has operations in Germany, Italy and Sweden.

Park says the new small diesel is being sourced from a GM plant in Europe. There currently are no plans to produce the mill in Korea, although the possibility isn’t ruled out.

“We’re looking at various opportunities, so maybe we could produce it in Korea,” he says. “We’re working together with GM Powertrain Europe on all kinds of products like diesel and gas engines and transmissions, most of which are used in Europe.”

Work also is being done to make GMDAT’s larger 2.0L Korean-made diesel Euro 5 compliant. Euro 4 standards prevail through 2010.

“It is more difficult to meet the U.S. diesel regulations,” Clark says. “We’re looking at the California market. It’s under study at the moment.”

He says the smaller European diesel engine is geared to the launch an unspecified new car in 2009.

“Putting diesel engines into vehicles is a big effort,” Park says. “It’s not a matter of simply switching engines. The body structure must be different to withstand the increased heat, more stressful vibrations and the additional weight.

“The diesel (mill) is heavier than a gas engine, and because of that there are passenger-safety considerations. All of these things generate big modification requirements for the vehicle. It takes a lot of effort.”

Steven Lee Clarke, GMDAT vice president-engineering, says integrating a diesel powertrain into the vehicle is complex.

“We have to make structural changes because of the different NVH (noise, vibration and harshness) characteristics of a diesel and its much higher torque level in the lower operating range,” he tells Ward’s.

“The diesel engine usually has higher mass, and we have to modify the cooling system because of the engine’s higher heat ejection.” The ignition system requires modification as well.

The ideal way to integrate a diesel powertrain is to start during the vehicle development stage, Clark says. That was the case with the Winstorm/Captiva CUV, Tosca sedan and Lacetti variants, which were designed as diesel vehicles that also could accommodate gasoline engines.

Park says that in addition to his team’s strong attack on diesel emissions, there also is an emphasis on engine-noise reduction.

GMDAT customers currently pay a 20%-25% premium for a diesel vehicle. For instance, the Lacetti in platinum trim equipped with a 1.6L gas engine is priced in Korea at $14,075, compared with $17,344 with the 2.0L diesel.

The Tosca equipped with a 2.0L gas engine sells for $20,796 in the base SE trim level and $23,806 with the diesel.

“As diesel engine technology improves, the cost difference is narrowing down,” Park says.

Euro 5 compliant engines should add no further cost to the vehicles, although the more-stringent Euro 6 probably will, he says. That’s because many auto makers are looking at injecting ammonia as a catalyst to break down nitrogen-oxide emissions.

However, Park sees the diesel’s inherent fuel economy and superior torque output as factors that will continue to offset the higher cost of the engine.

“Roughly with the same displacement volume or torque output, the diesel engine generates as much as 30% better fuel economy than gas engines,” he says, noting the thermal efficiency of an engine is dictated by its compression ratio.

“The higher compression ratio of the diesel engine results in more efficient fuel economy,” Park says. “Even as the emissions standards become more stringent, diesel is still a good choice. I see many opportunities for diesel.”