One of the most obvious signs of exhaust systems problem is a deep or loud rumbling sound. If you notice loss of power while driving or your car drives rough at idle (not moving)? That means there is a leak in the exhaust system (unmetered air gets into the engine) this will not be good for the environment and your wallet. When the exhaust leaks, your car engine works harder, when engine works harder, it requires more fuel and that will hurt your wallet. Delaying a needed exhaust repair can cost you more in a long run.