Regarding mid bass which is mounted on doors, we will have to consider it as an infinite baffle design and due to vagaries in shape unlike a proper sealed box, it is technically better to use drivers with qts above 0.7 which will be super rare in raw drivers.
So when you use raw drivers with lower QTC, then it is very important to properly damp the doors, and arrest any leakages to get the equivalent of a sealed enclosure, or else the QTS/F3 will be high and the mid bas will start to roll off a much higher frequency than its ability with a sharp slope leading to degrade in performance.
So the QTS will essentially vary for each car, not only by its door design, but also by the extent of damping and sealing done. Some enthusiast also build completely sealed enclosures for mid bass in doors. In US and other places they use kick panels which has other design benefits as well.