February 20, 1986

A car called the Excel is to go on sale in the United States for the first time Thursday morning. It is an unremarkable looking vehicle, resembling many of the small, efficient Japanese cars that have wrested a large share of the market from the domestic Big Three. The Excel, though, is not from Japan. It is being imported from Korea, where its manufacturer, the Hyundai Corporation, is one of the nation's leading manufacturing groups. The Hyundai Excel is the first of what could be a torrent of small cars made in Korea and other Asian countries headed for American shores.

Seven of the nation's biggest military contractors are competing for a share of the largest aircraft project on the horizon: A new jet fighter for the Air Force at a cost of up to $50 billion. The seven companies filed ''technical proposals'' with the Government on Tuesday - each one a 3,000-page compendium explaining how it would design a replacement for the F-15, the Air Force's current medium-range fighter. The proposed plane is now called the Advanced Tactical Fighter, or A.T.F. Already each of the companies has spent millions of dollars of its own money in jockeying for a role in the project. 'Program for the 1990's ''It is a must-win program,'' said Herbert F. Rogers, a general manager of the General Dynamics Corporation, one of the competitors. The others are McDonnell Douglas, which makes the F-15, Boeing, Grumman, Lockheed, Northrop and Rockwell International.

An American company operating in South Africa directly challenged apartheid today, saying it would offer financial and legal support to its employees who defy a law that calls for racial segregation of beaches. Bob White, managing director of the General Motors Corporation's subsidiary at Port Elizabeth, said in a letter to the editor of a newspaper there that his company found the city's beach segregation ordinance ''odious.'' Mr. White said he wrote the letter without consulting the corporate parent's headquarters in Detroit. He said G.M. would provide lawyers and money to defend in court any of its employees accused of violating the ordinance. In many parts of South Africa beaches are segregated by race, as are buses and restrooms.

King Hussein announced today that he was ending a yearlong effort to devise a joint peace strategy with Yasir Arafat, chairman of the Palestine Liberation Organization. In a three-and-a-half-hour speech on television, the King said the P.L.O. had proved to be untrustworthy in the effort to find a formula for talks with Israel. ''I and the Government of the Kingdom of Jordan announce that we are unable to continue to coordinate politically with the P.L.O. leadership until such time as their word becomes their bond, characterized by commitment, credibility and constancy,'' he said. There was no P.L.O. reaction. Palestinians close to the P.L.O. leadership said ''at no time during the negotiations did it mislead Jordan.'' [ In Israel, Defense Minister Yitzhak Rabin said the decision had created a ''historic opportunity'' and he called on Palestinians in the occupied territories to ''free themselves of the P.L.O.'' ] The King's announcement marked the second time that the he had tried and failed to join the P.L.O. Diplomats said it appeared to represent a setback for the decadelong United States-brokered effort to obtain land for the Palestinians in return for recognition and security for Israel.

The Federal budget deficits that have bedeviled the economy since the start of the Reagan Administration have reached a turning point, according to Government and private analysts. They have stopped going up, and as far as such experts can see, they are now going down. They are declining, they say, even without the contribution of cuts required under the new balanced-budget law, except for the small ones taking effect this year. An awareness of this shift has not yet become part of the conventional economic wisdom, because the turnaround is only now being detected by economic analysts in the Government and the private sector. The emerging trend, if it continues, means that the nation's most divisive economic issue would begin to recede.