If your vehicle is showing loud rumbling or roaring noise from under the car, here are the most likely causes and the parts you'll need to fix each one.
A hole in the exhaust, a broken flex pipe, or a missing catalytic converter will cause a loud roaring noise that gets louder as you accelerate and matches engine RPM. This is extremely common due to rust, bottoming out, or theft.
A failing wheel bearing produces a low-pitched roaring or rumbling sound that increases with vehicle speed. The noise typically changes pitch or goes away momentarily when you steer slightly to the left or right.
Tires that have worn unevenly (cupping) due to bad shocks or poor alignment can create a loud, rhythmic roaring noise that closely mimics a bad wheel bearing. The noise is tied to vehicle speed.
If exhaust hangers break or a heat shield comes loose, the exhaust system can vibrate directly against the floorboard, creating a loud rumbling noise inside the cabin. This often happens after recent exhaust or transmission work if parts aren't secured.
On rear-wheel or all-wheel drive vehicles, a worn universal joint or center support bearing will cause a rumbling noise and vibration felt right under the center console, usually worsening during acceleration.
Worn bearings inside the front or rear differential will cause a continuous roaring or whining noise from the axle area. The noise often changes depending on whether you are on the gas or coasting.