What tool is commonly used to unlock a vehicle door without a key?

The Slim Jim is a specialized tool designed for unlocking vehicle doors that lack electronic locking mechanisms. It is a flat strip of metal, typically about an inch wide, which can be maneuvered between a car's weather stripping and window to engage the locking mechanism inside the vehicle. This method works for many older car models where the locking mechanisms are accessible via this technique.

Understanding the use of other tools in this context helps clarify why they are less suitable for this particular task. While a hammer can cause damage to a vehicle, it does not offer a precise means to effectively unlock a door. A vice grip would be ineffective, as it doesn't provide the necessary reach or maneuverability to engage a locking mechanism. Lastly, a screwdriver isn’t designed for this specific purpose and could damage the lock or the door frame if used improperly.

Thus, the Slim Jim stands out as the appropriate and common tool for unlocking vehicles without a key due to its design and functionality.