Used-car dealer Tom Gunzelman says he approves of the U.S. government protecting its drug agents but does not recall volunteering to foot the bill.

"What does punishing 1.5 million innocent people accomplish?" he said angrily today. Gunzelman added that his business has been off by 60 percent since the U.S. Customs Service intensified vehicle inspections at all crossing points along the U.S.-Mexico border a week ago.

Agents are seeking information about Enrique Camarena Salazar, the Drug Enforcement Administration agent kidnaped Feb. 7 in Guadalajara, Mexico.

"We're going to start another Cold War with Mexico if this keeps up," Gunzelman said as he inched his Lincoln Continental the last few yards after a 90-minute northbound wait from Juarez across the Bridge of the Americas.

The economies of El Paso, population 500,000, and Juarez, twice as populous, are nearly as interwoven as those of Minneapolis and St. Paul, and week-long traffic jams at their three international bridges have begun to fray tempers of merchants, shoppers, workers, tourists, cabbies and political leaders.

"It is causing an extreme incovenience and an economic hardship," El Paso Mayor Jonathan Rogers said today in his 10th-floor office that offers a bird's-eye view of traffic backed up from the downtown bridge deep into the narrow streets of Juarez.

"We're really one city down here . . . . I'd like to see these inspections end tomorrow, but I'm just a mayor," he said.

Leaders of other U.S. cities along the 1,950-mile border have expressed similar concern, and their counterparts in sister cities in northern Mexico have been downright livid.

On the Juarez side, Mexican college students are distributing leaflets that urge motorists to "defend their dignity" by not crossing.

"Don't go to El Paso," say the flyers, which carry an endorsement from the Institutional Ruling Party, Mexico's dominant political party. "You do not deserve to be treated like a delinquent by American authorities."

Carlos Enriquez, manager of the Juarez Chamber of Commerce, which has endorsed the leaflets' message, said, "The people on the border have nothing to do with the kidnaping, and there's no reason for us to be affected by the international problems that have resulted."

Motorists, forced to wait three times as long as usual, have reacted with surprising stoicism and good humor.

Customs agents still manage wan smiles and occasional "thank yous" as they require each, or every other, motorist to open the trunk and/or hood. Compliance is almost always prompt and courteous.

"Mexicans and Americans who live in the Southwest are a littler slower on their temper," said Ruben Saenz, chief inspector of the Customs Service here. Since the detailed inspections began last Friday, he said, northbound traffic on the three bridges -- 36,000 vehicles on a normal weekday -- has decreased about 15 percent.

"The only thing that gets me is that you know we're not going to find anything. The professionals are smart enough not to try anything at the crossing points now," said an 11-year veteran agent, who asked that his name not be used. He said his week of checking trunks produced only five undeclared bottles of liquor.

As he spoke near an inspection booth where eight Customs agents and eight Immigration and Naturalization Service officers inspected six lanes of traffic, seven aliens brazenly climbed the 10-foot chain-link fence 30 yards away and illegally entered the United States. Not one officer left his post.

"We have hundreds jumping the fence right at the bridge each morning," Saenz said. "The border patrol has the whole area on camera. They just don't have the manpower to put a unit at the fence. They think it's more efficient to try catch them a few blocks away. I'd say they pick p maybe half."

Skepticism about the vehicle inspections is widely shared by El Paso merchants, especially those dependent on Mexican shoppers.

The U.S. government has made it clear that another purpose of the operation is harassing Mexican nationals in an effort to pressure the Mexican government into cooperating more fully with the kidnaping investigation.

Beth Hudson, a clerk in an El Paso store that sells second-hand clothes to an overwhelmingly Mexican clientele, said, "the two governments are both being stupid . . . acting like babies."

Retail business with Mexicans had been rebounding nicely from the 1982-84 border recession. In four years, the peso has been devalued a massive twentyfold against the U.S. dollar, but it has been almost stable in the last 12 months.

Also binding the two cities are about 200 American-owned assembly plants in Juarez that take advantage of cheap Mexican labor and send a variety of finished goods across the border with tariff paid only on the value added.