But the research shows how completely new types of automotive attacks could be on the horizon. For example, thieves could instruct cars to unlock their doors and report their GPS coordinates and Vehicle Identification Numbers to a central server. "An enterprising thief might stop stealing cars himself, and instead sell his capabilities as a service to other thieves," Savage said. A thief looking for certain kinds of cars in a given area could ask to have them identified and unlocked, he said.

In their report, the researchers don't name the make of the 2009 model car they hacked.

Savage and the other researchers presented their work to the , which is studying the safety of electronic automotive systems in the wake of last year's massive Toyota recall. That recall was prompted by reports of unintended acceleration in Toyota vehicles, a problem that was once thought to have been connected to electronic systems but ultimately was blamed on floor mats, sticky gas pedals and driver error.

With the high technical barrier to entry, the researchers believe that hacker attacks on cars will be very difficult to pull off, but they say they want to make the auto industry aware of potential problems before they become pervasive.

Car hacking is "unlikely to happen in the future," said Tadayoshi Kohno, an assistant professor with the University of Washington who worked on the project. "But I think the average customer will want to know whether the car they buy in five years ... will have these issues mitigated."