A pair of laser distance sensors are arranged to impinge a respective laser beam on a respective one of a pair of surfaces on a reference target installed on a car door to determine the extent of misalignment of a door latch and striker by determining the extent of any vertical door movement induced by such misalignment. The use of oppositely inclined surfaces eliminates the effect of small mispositioning of the reference target surfaces and the laser distance sensors. A side by side arrangement of the laser distance sensors can also be used to determine the door closing speed.