Parked in an area hard hit by auto theft, the cars look like any other in the neighborhood. Sometimes there is trash on the floor, or perhaps a university decal on the rear window. The keys may rest on a seat or dangle from the ignition. Within a few hours or days, a thief takes the lure.

As he slips behind the wheel and motors away, the stolen vehicle sends an electronic tracking signal to police dispatchers. In short order, officers kill the engine by remote control and descend on the suspect. Police say these high-tech "bait cars" save time and resources. In Minneapolis, for example, the successful program is run by an investigator and an unpaid intern.

When D.C. police adopted the program last year, the aim was to help curb one of the worst auto theft rates in the country. But the department's nine bait cars, which cost $324,000, rarely have been deployed because of a legal concern. Unlike other police departments that rely on technology to alert them to any thefts, D.C. police are required to assign officers to monitor their cars at all times.

One officer keeps a car under constant watch, four others are positioned nearby in two cruisers and a sixth is stationed at police headquarters to send the electronic signal to kill the car's engine. In more than a year, D.C. police have made 18 arrests. The bait cars were used three times last month. They are deployed so infrequently that some commanders have turned to using them to secretly record undercover drug deals, police officials said.

Police said the heavy surveillance is required by the department's lawyers, who are concerned about being sued if a bait car hit a bystander. The lawyers were particularly worried because a high percentage of the city's auto thieves are juveniles with little experience behind the wheel, police said.

Agencies regarded as leaders in the field of bait cars, including police departments in Arlington County and Minneapolis, deploy cars without surveillance, sometimes for days or a week at a time. Police officials in both agencies said they felt the benefits of the cars outweighed any potential for harming bystanders, particularly because the cars can be shut down remotely.

"Getting sued is the chance you take when you do something proactive," Minneapolis investigator Wayne Johnson said. "For the most part, it works the way it should. It's a good product."

D.C. police Lt. Brian McAllister, who started the District's bait car initiative last year, said he wanted to create a program similar to those in Arlington and Minneapolis. "But I had to come up with a plan that was acceptable to put vehicles out on the street, liability-wise," he said. "You can't really put a vehicle out there and then wash your hands of it."

Disappointed with the program's effectiveness, McAllister said he would "like to see the agency as a whole revisit the issue of deployment and how we use them."

Bait cars are gaining popularity among police agencies across the country. In the Washington area, Loudoun and Montgomery counties have bait cars. Prince George's and Fairfax county police are obtaining the vehicles, officials said.

At D.C. Council hearings and in community meetings last year, police heralded the cars as an easy way to curtail auto thefts. The cars would lead to iron-clad arrests because video cameras and microphones hidden in the vehicles would record a suspect's image and voice. Police also can remotely lock the cars' doors, helping to prevent the suspect from fleeing.

McAllister, who heads the central auto theft unit of the D.C. police, said he began trying to get the bait cars in 2003 and applied for federal grants. The department obtained $294,000 in grants from the U.S. Justice Department to buy cars and equipment. The nonprofit National Capital Police Fund, created by the nonprofit Federal City Council, donated $30,000, records show.

D.C. police bought the most popular stolen vehicles, including Fords, Jeeps, Chryslers, Dodges and Toyotas.

In May 2004, police deployed their first three bait cars. But when officers put one on the street for the first time and allowed it to be stolen, they lost the car in traffic. Suddenly, the sedan's tracking signal evaporated. It took police two days to find it. An $80 videocassette recorder in its trunk had been stolen.

Technicians eventually fixed and upgraded the cars' technology. Three months later, detectives hit the streets and quickly made 12 arrests -- five of them of juveniles. McAllister said the central auto theft unit was borrowing officers from the city's seven police districts to handle the cars.

"We had a car out almost every night," McAllister said. "It was really working great."

But technological problems cropped up again, he said, and police decided to upgrade the computer software and tracking devices. As the cars were retooled, police deployed them sporadically. By April, grant funding had allowed the department to add six cars to the fleet.

About that time, top police officials removed the bait cars from the centralized auto theft unit and sent them to the seven police districts. They hoped commanders would be able to deploy them more often and react quickly to reports of thefts and community complaints. But commanders and auto theft detectives found that they did not have enough personnel to make the program work. They also found it hard to justify putting six officers on a single car to deter auto thefts when they were battling more serious crimes, they said.

Statistics show the cars were deployed 13 times in June and July. In May, the cars were deployed about 20 times. In April, they were used twice. The most recent arrest in a bait car was more than a month ago, McAllister said. Before that, he said, police last made an arrest in April or May.

The infrequency of deployment frustrates D.C. Council member Phil Mendelson (D-At Large). He said he expected the cars to generate "hundreds of arrests" in their first year.

"I'm disappointed to hear there are so few arrests," Mendelson said. "I've always thought the bait car program was an excellent program. The problem with stolen cars is just enormous."

D.C. Police Chief Charles H. Ramsey conceded that the cars were difficult to deploy but said the vehicles were just one tactic to fight auto theft. He noted that car thefts in the District are down 26 percent from last year, with the city recording 3,666 auto thefts through July.

"It's a crime-fighting tool; it's not the end-all," Ramsey said, adding that he likes putting more officers on bait cars because it helps ensure that suspects don't slip away. "We have to find the balance. It's just one of many crimes we investigate."

Arlington police, who in 2002 were the first in the area to use the cars, credit the initiative with helping to reduce the county's auto theft rate 30 percent -- to 493 last year. Forty people have been arrested in the bait cars, and 31 have pleaded guilty in court, police said. Cases against the remaining nine are pending, police said.

Department officials, who declined to say how many bait cars they have, said the cars also deter thefts because suspects don't know what they are stealing. Officers may soon put up signs in some neighborhoods with warnings about bait cars to try to scare off thieves.

"We don't have to spend any additional manpower on watching the cars," said Matt Martin, an Arlington police spokesman. "We don't have to have a team of detectives sitting on it. The cars are always out there. . . . We're very happy with them."

Minneapolis police, who have been using the cars since 1997, said no bystanders have been hurt in accidents and police have made 240 arrests. Auto thefts have dropped 38 percent since they began using their fleet of more than a dozen bait cars.

"We wanted it so it would be cost-effective," said Johnson, the investigator who runs the program. "The days of surveillance for auto theft are over."

Lt. Brian McAllister shows video of a suspect in a bait car. Under the D.C. program, 18 bait car arrests have been made, with the most recent one more than a month ago, McAllister said.