FREMONT, Calif. — Workers have expressed grave disappointment in General Motors Co. and Toyota Motor Corp. after the closing of their joint venture in California left 4,700 without jobs.

After some 25 years of operation, the last Toyota Corolla car came off the assembly line at New United Motor Manufacturing Inc. April 1.

The equally owned joint venture, which operated as a symbol of cooperation between Japanese and U.S. carmakers, was the only Toyota-operated plant with workers represented by the United Auto Workers union.

In spite of union representation, however, workers seemed dismayed by the apparent lack of effort from both automakers to provide them with a proper severance.

“After all of their negotiations no one spoke up for us, and they eliminated the cash out,” Randy Gonzales, 57, who worked at the paint repair center at NUMMI in Fremont, told Kyodo News.

Workers at NUMMI would have received an average $54,500 in severance pay under the original agreement, with payment ranging from $21,000 to $68,000 mainly depending on their length of employment. But the latest agreement changed the deal from a seniority-based package to a retention package whereby cash would be provided to those who worked from Oct.1 to April 1.

The retention package does not take seniority into account, nor does it adequately accommodate the needs of workers on leave due to job-related injury, or long-serving employees with only a few years left before retirement. As a result, the average amount being paid to NUMMI workers under that system is only $21,000.

“They really should have had the severance package based on seniority instead of this retention package,” one male employee who worked at NUMMI for 18 years said on condition of anonymity.

Much of the blame from the assembly floor has been directed at GM for pulling out of the plant’s joint venture in the first place in 2009 following bankruptcy.

“GM screwed everything up when they abandoned us,” said Ray Guzman, a long-term worker at the NUMMI paint repair center. “Someone who’s been here a year is going to walk away with $18,000 and I’ve been here 10 years, and they give me $20,000. Now what am I supposed to do with that?”

The Fremont, Calif.-based plant was created in 1984 at the height of friction in the auto industry between the United States and Japan. NUMMI is expected to be liquidated, but there is no fixed plan on the use of the plant site.

Despite strong local opposition to the closure, Toyota did not change its decision to withdraw from NUMMI, citing the difficulty of operating the plant on a financially viable basis after GM withdrew following its bankruptcy in June last year.

While many look to GM for answers and restitution, some among the newly retired and laid-off thousands look to Toyota as well for an explanation.

“I feel betrayed, I really do,” said Gonzales. “Last year they got a $56 billion cash reserve and you mean to tell me there is no way they could have kept us open…that there was nothing they could have done?”

While some workers raged about Toyota’s decision to let go of NUMMI, its president and CEO, Kent Ogura, thanked Toyota in a statement for ensuring “efficient production until the last day of operations” at the Fremont factory.

The UAW was also seen by many at NUMMI as being partly to blame for GM’s pullout in the first place, as the union came to own about 17 percent of the new GM in 2009 bankruptcy negotiations.

GM has offered no money toward the severance of workers at NUMMI since pulling out. Toyota, however, provided a total of $280 million to NUMMI to support the transition of its salaried and hourly workers who would stand to lose their jobs. Among the nearly 5,000 employees at the auto factory were about 3,700 members of the UAW Local 2244. The local’s President Sergio U. Santos could not be reached for comment on NUMMI’s closure.

An employee at the local 2244 UAW office who did not give her name told Kyodo News that the mood within the union since the closure was “very sad.” “Everybody’s very nervous because they don’t have a job,” she said. “You can’t find a job.”