BALTIMORE, DEC. 6 -- The owners of a Prince George's County lot that sells expensive used cars were acquitted in federal court today of running a large-scale money-laundering operation for drug dealers through their business.

The sweeping acquittal on all 52 counts in the complex case came after the jury deliberated almost five days in a trial that started in September.

The three owners of the car business, Capital Imports, of Seabrook, wept and hugged the jurors after the verdict. The owners, all brothers from Iran, expressed relief but said publicity surrounding their arrest and trial had ruined their business.

"We are going back to Iran in the very near future," said Davood Sahiholnasab, 30, whose Anglicized name is David Sahih. Acquitted with him were brothers Nasser Sahiholnasab, 25, who calls himself John Sahih, and Ali M. Sahiholnasab, 28, known as Allen Sahih.

The prosecution contended that the brothers knew their customers were drug dealers intending to launder drug profits through car purchases.

Defense attorney Michael G. Middleton, in arguing to the jury, said the case was infected with "subtle racism," because the mostly white agents on the case assumed that the young, cash-carrying black car buyers at Capital Imports were likely drug dealers and would be viewed as such by the Sahih brothers.

"If you're black and young, you're considered a dope dealer," argued Middleton. "If you're white and young, it's considered that your parents are rich."

The Sahiholnasabs were indicted after federal and local agents descended on Capital Imports on July 21, 1989, in a widely publicized raid, seizing 48 cars and accusing them of hiding hundreds of thousands of dollars in cash paid to them for cars by known drug dealers.

Police said the brothers employed a technique called smurfing, by which they deposited larged amounts of cash in banks but avoided filing federal currency transaction reports by keeping individual deposits under $10,000.

Prosecutors Christopher K. Mead and Jack Purcell said the brothers hoped to avoid suspicion in this manner. Police, acting on a tip, conducted a sting operation, sending undercover agents masquerading as drug dealers to buy expensive cars for cash.

At the trial, about a dozen admitted drug dealers testified that they bought cars at Capital Imports as a way of laundering their drug profits.

Defense attorneys Middleton, Jane Macht and James C. Savage challenged the dealers' credibility, contending their testimony was tainted by promises of immunity from prosecution or recommendations for reduced prison terms.

The brothers also claimed they were unaware of federal reporting requireiments. They acknowledged that many of their bank deposits were in the range of $9,000 to $9,999 but contended they reflected actual sale prices on the cars.

Prosecutors said the actual prices were much higher for the Mercedes-Benzes, BMWs and other cars sold at the lot, and the brothers simply falsified sales records to avoid the reporting requirements.

The brothers countered that the sales prices reflected damage and vandalism, as well as the trade-in value on other cars.

After the verdict, juror Marilyn Lewis-Taylor, a federal employee in Baltimore, said the jury did not believe the drug dealer witnesses because of the "deals they cut" with prosecutors in exchange for their testimony.

"We knew they were lying," she said. "They were pure trash."

Lewis-Taylor said the jurors had voted 10 to 2 to acquit fairly early in the deliberatons, and much of the time was spent in getting the two holdouts to change their minds.