A bear got into a teenager's car, honked the horn and then sent it rolling 125 feet into a thicket, a Colorado family said.

Ben Story, 17, said he and his family were asleep in their home south of Denver when the bear managed to open the unlocked door of his 2008 Toyota Corolla early yesterday and climbed inside.

A peanut butter sandwich left on the back seat is probably what attracted the bear, Ben said.

It is not unusual for bears to open unlocked doors to cars and houses in search of food, said Tyler Baskfield, a spokesman for the Colorado Division of Wildlife.

"It happens all the time," he said. "They're very smart."

Once inside, the bear must have knocked the automatic transmission shift into neutral, sending the car rolling backwards down the inclined driveway and into the thicket, Ben said.

The door apparently slammed shut when the car jolted to a stop, he said, trapping the bear inside.

Neighbours had called emergency police dispatchers, and deputies freed the bear by opening the door with a rope from a distance. The bear then ran into the woods.

But Ben says he will need a new car because the bear trashed the interior trying to get out.