Exhaust Rear Muffler
WARNING: This page is about a different car, the 2017 Chevrolet Spark. However, it is still accessible from the selected car via links, so may be relevant.
The rear muffler is to reduce broad band engine exhaust noise. It is comprised of a series of perforated tubes and baffles to break up the sound waves and reflect them. It is made of stainless steel to protect the front muffler from corrosion.