A controversial bill to rak down on auto pollution in Northern Virginia ran into strong opposition today despite threats that the Washington suburbs could lose millions in federal funds if the measure is killed.

Representatives of state automobile clubs and gasoline retailers, along with legislators from rural and suburban areas took turns denouncing the bill, which would require annual tailpipe emission tests and force car owners to have their cars fixed if they flunk.

"It's an extremely expensive boondoggle to impose on the motorists of the commonwealth," John H. Wickstead of the Automobile Clubs of Virgina, told the House roads committee.

For most car owners, costs would amount to only a few dollars a year -- $4 for the test and a few more for minor repairs such as a carburetor adjustment. But the price could range up to $600 for big-ticket maintenance work, such as replacemenet of damaged catalytic converters -- the exhaust cleansing devices in most new cars.

To keep the cost down, the bill's sponsor, Del. Mary A. Marshall (D-Arlington), included a provision limiting the amount of repair work required after each inspection to $75. That did not placate Wickstead and other opponents, who also argued that the emissions tests -- mandated in Virginia and 28 other states under the federal Clean Air Act -- would likely do little to improve air quality in the region.

An Environment Protection Agency representative, Bruce Carhart, told the pack committee room that the tests would help reduce ozone -- the main component of smog -- from the atmosphere. He also warned the committee that Northern Virginia and the Richmond area, which also may be required to conduct the tests, could forfeit at least $128 million in federal air and water pollution funds, millions more in highway construction money and face a cutoff of EPA permits required for major construction projects in the regions if the bill fails.

Carhart said 22 other states, including Maryland and the District of Columbia, had already adopted the emissions program with little or no complaint.He got some reluctant support from Secretary of Commerce and Resources Maurice Rowe, a member of the Gov. John N. Dalton's cabinet. Rowe told committee "We come here with regret,' but then urged them to pass the bill because of the threat of federal sanctions.

Two Northern Virginians were among the committee members who grilled Carhart and other proponents. Del. Earl E. Bell, a Leesburg auto dealer, questioned why motorists in his rural county should be forced to undergo the tests. Carhart told him Loudoun was considered part of the Wasington metropolitan area and that the county would have to petition EPA formally to seek removal from the requirement.

Fairfax Del. Robert E. Harris, a conservative Republican, suggested the tests may be part of a government policy "to force people out of their cars," which prompted sponsor Marshall to respond, "It's a Commie plot, Bob."

Committee Chairman Orby L. Cantrell (D-Wise) attempted to exile the bill to a subcommittee dominated by Bell and other rural opponents. But after Marshall protested, Cantrell agreed to have a larger subcommittee consider the bill.

"It's breathing -- and that's better than I thought it would do," said Marshall afterward, adding that she had little stake in the bill's passage, "Half my people are for it and half are against it," she said.