Some exhaust systems are made of stainless steel, including the muffler. These exhaust systems can last virtually “forever”. Mufflers made of regular materials last 5, 10, 15 years. Many rust from the inside out. This happens in cars frequently driven only a few miles per trip. The water condensation will end up rusting the inside of the muffler. Cars driven on longer trips more often heat up the muffler enough to “burn off” this condensation. Muffler life isn’t about years, or miles, it is about the habits of the driver and the conditions the muffler encounters.