I am going to try and fix my bodywork following a rear end collision,but even though this is the first ever body damage the car has sustained it looks like it was never symmetrical. Can some one who has a good car just simply put a straight edge across the rear, just below the bumper and check if it rests on the bodywork ridges on the inner side of the rear lights and then check if the distance from the straight edge to the corners of the bodywork outside of the rear lights is equal on both sides. I hope that makes sense.