When you hear the unmistakable fart-like sounds coming from your car, it may be caused by the vehicle's gas tank. These sounds are produced by air trying to fill the vacuum created in the fuel tank, which can cause pressure to build up. This pressure then needs to release, which is what makes the sound.
Using a fuel additive can help reduce the effects of gas tank farting. These additives can help with the fuel efficiency of your vehicle, as well as helping to lower the emissions from your engine. These additives can also help with the odor that is associated with this problem.
Another reason why your car might be smelling like farts is due to the smell of a dead animal. A rat is a common culprit of this symptom, especially if the rat is decomposing in your engine bay. You should check your vehicle's engine, radiator hoses, and the cabin air filter. This will allow you to spot any animals that may be trapped in your car's engine bay.
Finally, you can use a product called Ozium spray to remove the odor of a dead animal from your air vents and heater vents. This will kill any molds and mildews that are growing inside the air ducts. To use this product, simply pour the Ozium spray into the car's air vents and heater vents and blast them for a couple of minutes each. It is recommended that you turn the AC on while this is happening, as this will keep air moving and prevent the build-up of moisture that leads to a foul odor.