Besides the smell of rotten eggs from sulfur emitted from the engine, you can also experience the smell of burning rubber or worn-out brake pads. This may sometimes be evident by smoke or a bad smell inside the cabin. This can be fixed by checking under the hood for loose belts and checking the brake pads soles. Additionally, molds, fungi, bacteria, and other micro-organisms can also make your car produce a bad smell. Bacterial growth often occurs behind the evaporator's dashboard panel. As a result, the air conditioner produces a foul smell.