There are several ways to open cars without using a key. Each method requires some form of skill and equipment. When locked out of your car it is important to call someone experienced to make sure they don't damage your door, weather stripping, or paint.
The most common method is to use an air wedge and a reach in tool. To do this you first slide an air wedge carefully in between the door and the frame while making sure to avoid the weather stripping. You then inflate your air wedge just enough to create a gap to insert your reach in tool. At this point you have a few options for unlocking the vehicle.
The method that works most often is triggering the manual lock. There are several styles of manual locks, which vary in difficulty. Some require a reach in tool with a loop at the end to be able to pull them up. Typically, however the manual lock can just be pushed or pulled with your standard reach in tool to unlock them.
Here are other techniques to open a car with a reach in tool:
While there are many methods for using reach in tools, some factors can make a car more difficult to get into. Things like having a difficult type of manual lock, re-locking locks, broken locks, heavily tinted windows, and tool racks that hang above the door are a few examples. Sometimes using a reach in tool may not be the right choice.
Picking can be a good option depending on the type of vehicle and the skill of the picker. In simple terms picking cars requires a pick to manipulate the wafers inside the lock. A tension bar then turns the lock once the wafers are properly aligned. Picking is by far the best choice for getting into semi trucks. It is also a good choice for getting into certain American cars. It can be a good choice for other cars too based on the skill level of the picker.
A slim jim is a tool that is commonly used but often not a good idea; many people who aren't trained to open cars try to use them. A slim jim can damage the components inside your door and pull out wires. To use a slim jim, you first insert your tool in between the weather stripping and the bottom of the window. You then dig until you find the bottom of the lock and pull it up. This is a risky choice that is not often recommended.
Lishis are the best method for getting into a car. To use a lishi, you insert it into the keyhole on the door. You then apply tension and use the markings on the lishi to feel each wafer. If the wafer feels binded, push it in. If it feels springy, you skip it. You keep repeating this process until the lock opens. The only problem with lishis is that it is difficult to get a lishi for every type of car lock, as there are so many. If you have the correct lishi and enough skill, you should be able to get into any car fairly reliably.