Chrysler Corp. reported yesterday that it lost $66.9 million in the last three months of 1981 and $475.6 million for the entire year as costly rebate programs squeezed the profit out of the company's improving sales.

The company sold 840,813 passenger cars in the United States last year, up 6 1/2 percent from 1980. Car and truck sales last year totaled 1.28 million, a 4.7 percent improvement.

These gains and continuing cost reductions and asset sales enabled Chrysler to hold its losses to $475.6 million ($7.18 a share) on total sales of $10.82 billion last year, compared to the record $1.7 billion loss on $9.23 billion sales revenues in 1980. The loss in the final quarter of 1980 was $235 million.

Chrysler wound up with a 9.9 percent share of U.S. car sales, including imports, last year compared with 8.8 percent in 1980.

General Motors Corp. said it made a $333 million profit last year, while Ford Motor Co. had a $1.06 billion loss. Yesterday, the two top auto producers reported increases in mid-February car sales, but Chrysler and the rest of the domestic industry lost ground. Total domestic auto sales in mid-February were down 1.4 percent from the same period in 1980 and the daily selling rate was the worst for that period since 1961.

Like scarred war veterans who have seen the worst, Chrysler officials talk optimistically now about the outlook for 1982 even though a significant recovery in sales is not expected until the second half of the year, according to most auto analysts.

"I think we're out of the woods," Chrysler Chairman Lee A. Iacocca told reporters at the National Automobile Dealers Association convention in Atlanta this week.

"There is a good chance we will be in the black in 1982; we hope to wind up with a profit of about $150 million this year," Iacocca said. And that prediction doesn't include the anticipated profit and future interest earnings from the $348.5 million sale of the company's tank division to General Dynamics Corp.

The "if" that still clouds Chrysler's future is the continuation of a three-year car slump. After making severe cutbacks in its workforce and plants, Chrysler has reduced its operating costs to a minimum and believes it can profit with even a slight recovery. The company said it has raised some $200 million so far through a financial control program intended to convert assets into cash and provide closer control over inventories.

Chrysler said it had $404 million in cash and marketable securities on hand at the end of 1981, up from $297 million a year earlier.

But it needs a strong rebound in auto sales to return to profitability and Iacocca isn't letting up in his criticism of administration and Federal Reserve Board policies that he sees as blocking the recovery.

The company said that it sold 16,556 cars in the middle 10 days of February, down 14.2 percent from the mid-February period the year before. Its sales so far this year are down 13.1 percent from the same period in 1980.

In a related development yesterday, hourly workers at Ford Motor Co. were approving a tentative concessions contract negotiated by the company and the United Auto Workers by about a 4-1 margin, the union reported.

With 14 units from 56 locals having completed voting late Tuesday, the vote was 4,208 in favor to 1,068 against the pact that asks workers to give up paid personal holidays and defer cost-of-living allowances, the union said.

Some 170,000 Ford workers in 94 units are eligible to vote on the agreement reached Feb. 13 after weeks of bargaining. Voting will wind up Sunday and union officials have said that, if approved, the contract will go into effect Monday.