Cars are manufactured with all the security measures and protection gears. The rear bumpers in cars like the Buick Grand National rear bumpers are installed and bolted towards the rear end of the vehicle, helping the car absorb any kind of impact caused due to crashes or untoward mishaps. The Buick Grand National rear bumper cover or the custom rear bumper is made of plastic, high quality ABS plastic or carbon fiber. These aftermarket bumpers are available in various bumper styles that can be easily bolted onto the lower rear portion of the car. The Grand National carbon fiber rear bumper comes with a cut out to allow your exhaust tip to exit the vehicle.