A friend of mine did something similar, but went a lot further. He asked a friend of his if he could borrow his car. The friend said it was okay and that the car was in the parking lot with the keys in the ignition (this was in a small town where nobody locked their cars). He went to the parking lot, found the car and drove away. The place where he was going was about an hours drive away, and when he was about half way there, he met a police car going the other way. He thought nothing of it, until the same police car came up next to him from behind and he was told to pull over. The police asked if that was his car, and he told them that it belonged to a friend and that he had his permission to borrow it. The police said that the car had been reported stolen. They escorted him back to town and found another identical car with the keys in the ignition in the same parking lot where he had taken the car. They called his friend and he confirmed his story, so no charges were pressed.
The TOG