WASHINGTON - Computer geeks already knew it was possible to hack into a car's computerized systems and potentially alter some electronic control functions.

But new research to be presented next week shows the vulnerabilities are greater and the potential for mischief worse than believed, in a wake-up call for the automobile industry.

Chris Valasek, director of security intelligence for the security firm IOActive, and Charlie Miller, security engineer for Twitter, found these vulnerabilities in cars' on-board computer, a mandatory feature on U.S. vehicles since 1996.

They found that by accessing this device, which sits under the steering wheel, someone with a brief period of access, like a parking attendant, could hack the car and reprogram key safety features.

"We had full control of braking," Valasek said.

"We disengaged the brakes so if you were going slow and tried to press the brakes they wouldn't work. We could turn the headlamps on and off, honk the horn. We had control of many aspects of the automobile."

The pair, working with partial funding from the U.S. government's Defense Advanced Research Projects Agency, also manipulated a vehicle's steering by hijacking the "park assist" feature which was designed only to move slowly in reverse.