But even when it works, there are still errors to fix. Cars have complex curves, and even the slight movement of my camera between shots (I always handhold these) slightly changes the perspective on those lines and curves. Photoshop can do a magnificent job of stitching images together, but I always have to check the seams and fix pixels that don't match up. The resulting image is also much larger than a single-shot image would be. Many of my stitched car shots are around 36" at full-print resolution!
So it's a little tedious, but totally worthwhile.