The Teamsters union reached a tentative agreement yesterday on a new four-year contract with the major car-hauling companies, averting a strike that could have crippled delivery of new cars to auto dealers nationwide.

James P. Hoffa, emerging from an all-night bargaining session in Arlington, called the agreement "the first major step of the Teamsters union coming back."

The agreement will be a major political test for Hoffa, who was elected president last December on a pledge to restore the power the 1.4 million-member union had under his father, the late Jimmy Hoffa.

Since his election, Hoffa has been telling friend and foe alike in the union to judge him by the results he achieves at the bargaining table. The agreement with the car haulers was the first major contract the union has negotiated since the election.

The agreement covers more than 12,000 International Brotherhood of Teamsters drivers, mechanics and yard workers at 17 car-hauling companies that handle more than 90 percent of all new-car deliveries to dealers in the United States. Canadian car haulers are covered by a separate contract that expires in October.

The agreement must be ratified by the union membership, a process that is expected to take about a month.

R. Ian Hunter, executive director of the National Automobile Transporters Labor Division, which negotiates for the 17 employers, said the new contract would continue to keep Teamsters workers the highest-paid in the industry. He called the agreement a compromise in which neither side got everything it wanted. "We are especially pleased that a strike has been averted and that a disruption of service to our customers has been avoided," Hunter said.

One of Hoffa's major critics, Ken Paff, leader of the union dissident group Teamsters for a Democratic Union, called the agreement a concessionary contract. "I'm really surprised he would sign a concessionary contract rather than strike," Paff said.

The new agreement calls for a lump-sum payment of $1,500 in the first year and 50 cent-an-hour increases in each of the last three years of the contract. Top wages in the industry are approximately $20 an hour, but the actual pay is based on a mileage formula.

Union drivers currently earn an average of $68,000 a year in wages and benefits, but some can earn as much as $100,000 with overtime, according to the union. Car haulers are among the highest-paid truck drivers in the union.

The biggest gain, according to Teamsters spokesman Chip Roth, was in the pension area, where car haulers will now get $2,000 a month after 25 years' service, regardless of age, and $2,500 a month plus free medical coverage after age 55 with 25 years of service.

"It's a major victory for the union," Roth said. He said union surveys at the start of the negotiations showed that improving the pension benefits was the biggest issue among the members.

In addition, Roth said, the union forced the companies to drop demands for part-time workers and a two-tiered wage system. The companies also agreed to a union demand that they not use Mexican trucks and drivers to deliver cars after Jan. 1, when the U.S.-Mexico border is opened to international trucking under the North American Free Trade Agreement.

The union did grant the companies "flexibility" to allow mechanics and yard workers to be assigned weekend work. It also allowed the companies to pay drivers half pay when hauling used cars on what are known as back hauls -- return trips from delivering cars. TDU's Paff called both items concessions.

CAPTION: Teamsters President James P. Hoffa, right, shakes hands with R. Ian Hunter, executive director of the National Automobile Transporters Labor Division, after they reached a tentative accord on a new contract for 17 car-hauling companies.