The police handcuff a prisoner, place him in the back seat of a four-door sedan police car, and close all the doors. The controls in the back seat are disabled so the prisoner cannot use the inside controls to open the back doors, nor operate the back windows. There is a barrier between the front seat and back seat, which prevents the prisoner from accessing the front seat area. The back seat cannot be folded down to access the trunk, and there is no sunroof. The police car cannot be remote-controlled, nor hacked electronically. The police car is of normal construction, with no material defects. The police leave the prisoner alone in the police car. Within five minutes, by himself, without tools, and without damage to the police car, the prisoner escapes from the police car. How? I am looking for the simplest explanation.
Now that the puzzle is solved, this really happened. A news article is excerpted in the spoiler below. (warning, this gives away the answer entirely)
Police: Handcuffed kidnapping suspect opened cruiser door through open window ... ST. THOMAS — A kidnapping suspect who was handcuffed and placed in the back of a police cruiser managed to escape by reaching through the cruiser’s open window and opening the door, according to court records.
This puzzle was not well-received, so I welcome comments on how it could have been improved.