The present-day car manufacturers using glues will have the seam located where it is hidden from view, such as lapped seams from sail panels up on top of the roof, finished with a rubber insert or flowable seam sealer. One thing these manufacturers do not do, is to have a seam down through the middle of a panel, like is commonplace in patch panels. The issue here is that a glued seam requires an overlap. When installing a stepped flange on one side of the seam, once the panels are glued together this leaves one panel thickness on one side of the joint, and two panel thicknesses on the other side where the stepped flange is located. With these different thicknesses you have adjacent areas that have differing expansion rates. So any exposure to the sun, will result in the single thickness expanding quicker than the two thickness, and contracting faster as it cools down in the evening. Once this happens over time, the seam will show a "ghost line" in the paint at the divide between the different expansion rate areas regardless of any filler or paints over the area. So despite all panels glued by GM, Dodge, Volvo, or whomever you'd care to throw in the mix, they do not produce a stepped seam through the middle of a door, quarter, or similar low crown panel due to the inherent possibility of ghost lines.
