Toyota Motor Corp. is expanding the roles of four executives in North America, including three non-Japanese, as Asia's largest automaker seeks tighter coordination in its biggest market.

Steve St. Angelo, executive vice president for North American engineering and manufacturing, will oversee all regional production. Ray Tanguay, chairman of Toyota's Canadian unit, is to oversee quality issues, and Jim Lentz, who will become chief executive officer of Toyota's U.S. sales arm on April 1, will oversee sales, marketing and product planning for the region.

"As the competitive environment continues to intensify we need to get to a point where we make speedier decisions," Jim Wiseman, a New York-based spokesman, said last week. "This is part of efforts to create a 'one Toyota' structure in North America."

Toyota is revamping its structure as it seeks to regain U.S. sales following a 6.7 percent slide last year after natural disasters in Japan and Thailand curtailed output of parts and vehicles. Toyota's U.S. sales gained 10 percent in the first two months of this year.

Unlike in Japan, Europe and China, Toyota's North American operations are split among a sales company, a manufacturing and engineering division, a corporate unit and finance arm.