Get into the habit of locking your patrol car doors with safety in mind. When you first get in your car, unlock all four doors with the power lock. Then reach over and lock your passenger door by hand. When you get out of your car on a call, lock your driver door by hand instead of using the power locks. This will leave both front doors locked, and both back doors unlocked. If you make an arrest and need to put your suspect in the back of your patrol car, your back doors will already be unlocked.
How many times have you tried to put someone in your back seat, only to realize that all your doors are locked? Now you have to fumble around finding your keys and unlocking the front door to unlock the back door, all while you are trying to control a potentially dangerous suspect. Your safety can become compromised while you take your attention off your suspect to unlock the car doors. If you utilize good door locking habits, you can minimize your vulnerability.