Real-estate agent Carol Ann Adams thinks of her car as a mobile office.
"I have a lot of miles on it, so I just thought I'd explore the option of finding one with less miles," said Adams.
After she hit the road in her upgrade, Adams noticed something stored in the Bluetooth connection: the previous owner's cell phone contacts.
"All my recent calls, calls that I received, it still didn't occur to me that I'd left it all on the old car," said Adams.
When drivers gear up to trade in or sell, most don't think about the secrets their car holds. But experts say they should.
From the built-in Bluetooth, to the navigation system, to the garage-door opener, CNET.com's Brian Cooley says today's vehicles are like rolling smartphones loaded with personal information.
"Think about it: Here's the car you traded in sitting on a used car lot. The garage door is programmed into the garage-door opener and your home address can be programmed into the GPS, if you didn't think about all this," said Cooley. "Well, that's a perfect, pre-made kit for a garage burglary."
The good news? Cooley says you don't need to be tech-savvy to "erase" your ride. It only takes minutes.
Each car is a bit different, but the general process is the same. To steer clear of danger, look for the GPS main menu.
"Typically, there's a separate menu beyond that that will delete information," said Cooley. "It's about three or four keystrokes on the touch screen, or whatever kind of physical buttons are in the vehicle."
Pressing a few buttons is all it takes to re-program the garage-door opener, too. That's something Adams did remember to do.
"I just looked in the manual, and you just push the program and the reset button and it resets," said Adams. "It took two seconds."
Finally, don't forget to clear the phone system. While "hands-free" is a hot feature: "There are all your contacts stored in the car, so this is the mother lode of personal privacy invasion in vehicles," said Cooley.
To dump those contacts "call up" the Bluetooth menu. There should be a simple "delete" command.
"You un-pair it so it no longer works, and that will also remove the data from it," said Cooley.
If you think your dealer will clean up after you, don't be so sure. The National Automobile Dealers Association was contacted and was unaware of the issue.
Before you trade in or sell your car, don't forget to clear out the glove compartment. It could contain paperwork with things like your name, address and insurance information.