Boosting the efficiency of the company's Korean plants is a top goal. "We need to enhance our productivity," Rocha says.
But weak demand from Europe, a key market for GM Korea's small cars, and an increasingly unfavorable currency rate are limiting production volumes at its factories. Moreover, a new labor agreement curtails the plants' shifts, also squeezing volume and productivity.
Slumping sales in Europe have forced the company to idle its assembly plant in the southwestern city of Gunsan for nine days this month. That plant, which makes the Cruze small car and Orlando crossover, ships about 40 percent of its output to Europe.
In all, about 84 percent of GM Korea's output is exported. The local currency's rise crimps profits on those overseas shipments. If GM were to raise prices to compensate, that would make those vehicles less competitive against rivals' offerings.
In part to offset that overseas softness, GM Korea aims to boost local sales. The company targets a South Korean market share of 15 percent within five years and around 20 percent starting in 2020, up from about 10 percent now, Rocha said.
Meanwhile, GM Korea is testing out a new work schedule that reduces factory hours. The new schedule is the result of a tentative labor contract that includes concessions, won by Korean auto workers after a strike last summer, which mean plants will be running for 17 hours a day, not 20.
The labor deal also affects rivals Hyundai Motor Co. and Kia Motors Corp. In March, the first month under the arrangement, total South Korean automobile production fell 13 percent from a year earlier while exports tumbled 16 percent. GM Korea's output contracted 4 percent.
South Korea's Ministry of Trade, Industry and Energy blamed the declines on "fewer working days and reduced working hours."
But a final pact is far from a done deal. "This is conditional," Rocha said. Last summer's agreement is contingent on getting the same output without expanding capacity or adding people, he said.
That could be accomplished by accelerating line speeds and cutting break times, Rocha said. After a trial period at the reduced hours, management will meet with union leaders to hammer out details of a final agreement to be implemented in the first quarter of next year, Rocha said. The trial period runs for three months, starting in March.
"We need a collaborative relationship with the union leadership. And, second, we need to keep our competitiveness," he said. "No free lunch, right?"
What happens if labor and management can't reach an acceptable solution? "This is a boomerang," Rocha warned. "They gain today, but they lose tomorrow."
He said: "We cannot lose volume. If we lose volume, it means the volume will be allocated somewhere else" in GM's global network.
GM is reviewing its allocation of global production to South Korea anyway, because of the wild card of North Korean leader Kim Jong Un.
North Korea has issued increasingly shrill threats of war in recent weeks, and GM CEO Dan Akerson is taking them seriously.
"We are making contingency plans for the safety of our employees to the extent that we can," Akerson said in an interview on CNBC this month. "Beyond that, it's difficult to shift production."
Akerson's remarks fanned tensions with union leaders. They saw his comments as a veiled threat, boding ill for smooth implementation of the scaled-back working schedule.
"It is a message by Akerson to the union saying, 'Don't make excessive demands,'" union spokesman Choi Jong-hak told Reuters.
"They want to make the union feel jittery," Choi said. "It is a threat."