Mazda Motor Corp. announced Wednesday that President James E. Miller has been replaced by his 38-year-old deputy, Mark Fields. Fields, who became vice president only two weeks ago, has stepped up to the top post as the youngest to do so in the firm's history. Miller, 58, resigned from the presidency and the directors' board for "personal and health reasons," a Mazda spokesman said. Speaking at separate news conferences in Hiroshima and Tokyo, Fields said he will work toward improving Mazda's brand image and bringing greater efficiency to the firm's operations. Noting that actual achievement and experience are more important than age, he said he will lead the company with confidence but not arrogance. Fields, a Harvard Business School graduate, currently serves as vice president of Ford Motor Co., which holds a 33.4 percent stake in Mazda, Japan's fifth-largest automaker. After working as managing director at Ford Argentina S.A., Fields joined Mazda Motor in August 1998 as senior adviser and became senior managing director in charge of marketing, sales and customer service in June 1999, before becoming vice president on Dec. 1. Fields is the third foreign president to Hiroshima-based Mazda Motor, following Miller and Henry Wallace, Ford's group vice president for the Asia-Pacific region. Mazda is on track to post a record net profit of 40 billion yen at the group level in the fiscal year to March 2000, Miller said, despite the strong yen's impact on exports. Mazda, which has no European manufacturing base, draws about 40 percent of its revenue from exports, more than any other Japanese carmaker. Mazda expects domestic sales to rise 5 percent in calendar 2000 from 1999's estimated results to 335,000 units, and sees exports going up 2.4 percent to 515,000 vehicles. Production is predicted to jump 6.2 percent to 825,000 units in 2000.