After a rear end collision, a narrow gap between the quarter panel and the door may indicate:

A narrow gap between the quarter panel and the door following a rear-end collision is an important indicator of potential structural damage to the vehicle. When a collision occurs, particularly in the rear, the force of the impact can cause misalignment of various components of the vehicle's body.

In this case, if there's a gap between the quarter panel and the door, it suggests that the quarter panel itself might have shifted or been pushed inwards. This type of deformation could affect how the quarter panel aligns with other parts of the vehicle, such as the floor structure. Damage to the floor could further exacerbate this alignment problem, creating an inconsistent seam between adjoining panels.

So, observing that narrow gap can lead an appraiser to conclude there’s a likelihood that both the quarter panel and the floor have sustained damage during the collision, impacting the overall integrity and safety of the vehicle. Understanding these relationships between various parts of the vehicle is crucial in accurately assessing damage and estimating repair costs.