September 29, 1986

Detroit's high-stakes bid to spur car sales with low-interest financing has helped dealers sharply pare swollen inventories. But the cut-rate loans have attracted many thousands of drivers who otherwise would have bought used cars and that segment of the industry is now in a slump, with sales off as much as 30 percent in some parts of the country. ''We're all hurting real, real bad,'' said Irv W. Rohrich, president of the National Independent Auto Dealers Association, a Dallas-based trade group whose members sell only used cars. ''A lot of people have closed down in the last two months - they can't compete.'' As the cut-rate loans have reduced the number of new cars on hand, a flood of trade-ins has produced a ''dramatic rise'' in used-car inventories, said Jean-Claude Gruet, automobile analyst for Salomon Brothers Inc. And while some used-car dealers have responded by cutting prices, providing warranties and even offering cut-rate financing of their own, demand has remained soft.

These are days of triumph and days of disappointment for the President's master political strategist and Treasury Secretary, James A. Baker 3d. For 20 months, Mr. Baker carried the President's campaign to overhaul the tax system and, with the Senate's vote Saturday, Congress has responded with resounding majorities in both houses. But also on Saturday, during the final moments of the tax debate in the Senate, Mr. Baker was meeting in his third-floor conference room with fellow finance ministers of six American allies. There, the representatives of the allies' two strongest economies, West Germany and Japan, flatly and finally rejected Mr. Baker's weeks of remonstration that they cut their interest rates to help the American economy. As for whether the economy will be helped or hindered by the new tax-revision legislation, politicians and economists are unable to agree. [ Page D5. ] Mr. Baker's attentions now turn fully to the international arena, one that has proven infinitely more difficult than the American Congress he mastered, initially as the President's chief of staff and since February 1985 as his Treasury Secretary and chief economic policy maker.

Behind the rosy glow of rouge and the scent of perfume on any department store cosmetics floor, some not-so-pretty fights are taking place. Many cosmetic companies are locked in vicious battles for better retail locations and more space. The elbowing for prominence has become fiercer of late as newcomers march onto the market in ever-greater numbers. Last year alone, 41 new perfumes were introduced, including Obsession from Calvin Klein and Beautiful from Estee Lauder. But though new products have multiplied, display space has not. For a newcomer to fit on the floor, an old-timer must be moved or removed. ''Location and space, location and space,'' said Robert Barnes, president of Estee Lauder U.S.A. ''Retailers complain that that's all we talk about. It's because that's the bottom line.''

International American trade imbalances have to be reduced either through greater competitiveness of the dollar or increased growth outside the United States, Treasury Secretary Baker said on the eve of the I.M.F. and World Bank meeting. [ Page D1. ] The dollar fell briefly but then leveled off in response to meetings held before the annual monetary gathering. [ D4. ] Secretary Baker is encountering resistance to his international agenda even as he savors victory domestically with the final passage of the tax bill. [ A1. ]

Christian militiamen, reportedly backed by units of the Lebanese Army, have foiled an attempt by pro-Syrian militiamen to seize control of the predominantly Christian sector of Beirut. The police said 52 people were killed and 200 wounded in the fighting on Saturday, when rival militiamen fought pitched street battles for 13 hours. Artillery duels were reported today across the Green Line dividing the predominantly Christian eastern sector of the capital from the mostly Moslem west. Shells and rockets fell in residential quarters close to the line, but it was not clear which forces were involved.