Drivers often worry about new technology in their vehicles, and whether or not those GPS devices can end up acting like Big Brother. Early last Friday, Mercedes put its mbrace telematics system to the test, tracking down the two fugitives: Tamerlan and Dzhokhar Tsarnaev.

In a harrowing story told in The Boston Globe today, a Chinese immigrant who said his new Mercedes-Benz ML350 SUV was carjacked by the brothers, told a tale that sounded like a movie plot. He waited for the right moment to escape. It came when one of the brothers went into a gas station in Cambridge to pay for fuel and the other brother, momentarily distracted, put down his gun.

The man, who only wanted to be identified as Danny, in one motion unbuckled his seatbelt with one hand and opened the door with the other, and ran. He fled to a gas station across the street, and told the owner to call police.

When the police got there, he told them his car was equipped with mbrace, the carmaker's GPS-based system that can track stolen cars. He also had left his iPhone in the car.

Donna Boland, a spokeswoman for Mercedes, told AOL Autos a call came from the police just after 12 a.m. Friday. They put Danny on the phone, and he confirmed he was the owner by providing his PIN number.

Mercedes then relayed the location of the car to police, updating the location as it moved around the Boston suburbs. They tracked the car to Laurel Street in Watertown, where a gunfight ensued between police and the Tsarnaev brothers. A Laurel Street resident captured photos of the shootout, including a picture of the Mercedes attempting to run down police.

Boland said Mercedes reached out to see if it could help police any further, but they haven't been needed.

Privacy issues have come up over the use of tracking devices in cars. Given reports that the brothers were planning to head to New York to try and pull off another bombing, the police are lucky they found the car before they could leave Boston.

Back in 2003, Mercedes had success using mbrace to track down two toddlers who had been carjacked. The carjacker threw the mother from the car, and sped off with her children inside. The policeman who came to the scene also owned a Mercedes and knew it had a system that could track the car. With permission from the owner, Mercedes listened in and made sure the children were safe.

Boland said that Mercedes can no longer listen in on passengers inside the car. The communications system only turns on when the driver pushes a button, or when the airbags go off. When it is activated, the radio turns off and the dashboard has a flashing message saying the system is on.