There are many discussions around the safety of locking doors whilst driving, some argue that if it is locked it is more difficult to remove passengers in the event of a serious crash. When there is an impact, often the doors are pushed in and don’t open, whether they were locked or unlocked, the impact often damages doors which can jam them anyway.
Many car manufacturers now install “Auto-Locking” devises that activate once the vehicle is travelling at 20 kms per hour. The reason for this is that there have been many incidents over the decades of children opening doors whilst the car is in motion and falling out. Some cars are also fitted with an auto-unlock function, which opens the doors if the system detects the car has been in a crash.
20 years ago and more doors on older style vehicles would often swing open when driving around a corner, locking doors became a secondary way of ensuring the door would stay locked and people wouldn’t simply fall out going around a bend!
In the event of a car crash, the doors need to stay closed as this is how they absorb the impact, keep you from being thrown out, and help keep the roof from crumpling like a soda can. If the vehicle does roll over, the lock is a secondary means to ensure this.
From a safety perspective, it is advisable to keep doors locked to avoid “Road Ragers” that may attack the vehicle or passengers and keep you safer when driving in unsafe areas or especially when driving alone.