How to tell the difference between a Narrow Body and a Wide Body If you don’t have a tape measure to hand then the two most visual differences between a narrow and wide body car are around the rear lights and also the shoulder panel next to the seat. Starting with the shoulder panel, a narrow car will have a flat, vertical internal panel next to your shoulder. On a wide body car the GRP tub is extended into the cockpit to create a scalloped or chamfered panel to give more shoulder room. Th