What Is Car Exhaust?

Have you ever walked past an unnecessarily loud car and wondered – what makes it so loud? Or have you ever thought about where all the gasses from the internal combustion process end up? Perhaps it’s time to find out what is car exhaust and learn a bit more about the car exhaust system.

What Is Car Exhaust and Why Is It Important? 

The first thing you should know is that there is much more to the car exhaust system than just the exhaust pipe. There are many parts of the exhaust system that all work together to protect the driver and the passengers from harmful gasses. However, that is not the only role this system plays in your car. There are many more advantages of having a quality car exhaust system. 

It Takes Away the Harmful Gasses

Your car works thanks to many internal combustion processes. Think of it as thousands and thousands of small explosions that produce energy, but at the same time, they also produce harmful exhaust gas. This gas contains a lot of chemicals that could be dangerous. 

When you think about exhaust gas, you think about toxic carbon monoxide, carbon dioxide, nitrogen oxides, and hydrocarbons. Just imagine having to breathe in that mixture of chemicals each time you sit behind the steering wheel. That’s why the car exhaust system exits, to release exhaust gasses on the outside, away from the vehicle and your nostrils.

It Controls and Minimizes Noise

Besides gasses and chemicals, cars also produce a lot of noise. The fuel combustion process causes explosions which produce noise that needs to be restricted and contained. An exhaust silencer reduces the noise coming from the engine, and the muffler also has a significant role. Of course, high-priced cars and newer models will have better and stronger exhaust systems, and the noise will be significantly lower than with old models and used cars. However, the suppressors in an exhaust system in any average car will reduce the noise levels by 20-35 dB.

A Good Exhaust System Can Improve Your Fuel Efficiency

To some people who aren’t big car enthusiasts, it might seem strange that a car exhaust system and a car’s fuel economy could have something in common. However, your car exhaust system has a big impact on your fuel efficiency. Once the exhaust gas leaves your vehicle, your engine can take in more oxygen, and your fuel consumption is better. Oxygen allows your vehicle to breathe better and faster and generate more energy. And not only does your exhaust system improve fuel efficiency, but it also improves your engine performance.

What Are the Components of the Car Exhaust System? 

From the outside, it might seem that the exhaust pipe is the only component responsible for the regulation of exhaust gasses and noise. However, there are many more components that are just as important, if not more. All these components create a system that protects you and allows you to stay safe while driving:

  • Exhaust manifold,
  • Catalytic converter,
  • Muffler,
  • Resonator,
  • Tailpipe/Exhaust pipe,
  • Oxygen sensor.

Exhaust Manifold

The exhaust manifold or the exhaust header is the first component of the exhaust system in any car. It’s the starting point of the journey the exhaust gasses will have to go through to get to the outside of the car. They are positioned right at the engine, at the very start of the exhaust. The exhaust manifold is a cast iron metal part that connects the engine with all the other components of the exhaust system

If it’s not made of cast iron, it’s made of steel since those two materials can achieve to create special bends needed to increase efficiency. However, the exhaust manifold is often upgraded by switching heavy cast manifolds for tubular headers. The manifold connects to the engine through tubes. It has individual tubes on the side which connect to the engine cylinders. Each tube connects to a cylinder on one side of the manifold, but then they merge into the exhaust, and only one tube comes out on the other side. 

Catalytic Converter

The catalytic converter might be the most important element of the exhaust system. This is the component that keeps the driver and the passengers, as well as the environment, safe. It’s often referred to as “cat.” Ever since 1986, all car manufacturers are required by law to have a catalytic converter in all of their car models and all other passenger vehicles. Your vehicle will not pass the roadworthy inspection without one.

This component is vital for reducing pollution caused by cars and exhaust gasses. The catalytic converter transforms harmful gasses such as NOx, carbon monoxide, and unburnt hydrocarbons into environmentally friendly ones such as nitrogen, water, and carbon dioxide.

The way it does this is pretty simple, and it involves a few chemical reactions. For starters, the converter uses a catalyst that allows other chemicals to react while not changing its own makeup. This catalyst is a substance like palladium, platinum, rhodium, or some other chemical that can keep its integrity while making other chemicals react. The reaction converts carbon monoxide into carbon dioxide and hydrocarbons into water and carbon dioxides. Even though these chemicals are still not the best for the environment, they’re much better than unfiltered emissions from the engine’s combustion chamber


A muffler, also known as a silencer, is known for silencing or muffling the noise that is produced by the fuel combustion process. The muffler is located at the rear of the exhaust system, and there are many types of silencers. It works its magic in a few ways. The main way it eliminates noise is by redirecting airflow. The muffler uses porous, perforated tubes that create opposing sound waves to the ones the exhaust gas creates, and the sound waves cancel each other out. 

Another way in which a muffler could reduce noise is by adding special materials that help to absorb sound to the inside of the muffler. The noise coming from the car exhaust isn’t just an inconvenience to the driver or the neighbors – studies have shown it has an effect on public health since it’s been linked with causing heart issues. So, a quality, healthy muffler will not only eliminate noise and keep you healthy, it will improve the performance of your car on all fronts. 

An old car exhaust
Mufflers reduce the noise your car creates


A resonator is an optional component of the exhaust system. It’s not necessary to have a resonator in your vehicle, and your car will pass the roadworthy inspection even without one. However, it’s an extremely useful thing to have since it helps eliminate noise. It’s pretty similar to the muffler, and it even works in a similar way – it cancels out sound waves coming from the exhaust system by rejecting them in a specific frequency. A resonator can be placed either before or after the muffler or the silencer in the exhaust system. A resonator will not only help the muffler eliminate more noise, but it will also have a big positive impact on the fuel efficiency of your car, as well as your overall car performance. 

Oxygen Sensor

When talking about critical components of the exhaust system, oxygen sensors shouldn’t be forgotten. While their job seems pretty simple and straightforward – they measure oxygen levels in the exhaust system and the gas – they have one of the most important roles in the whole process. An oxygen sensor is usually located on the side of the catalytic converter or in the exhaust manifold. 

Oxygen levels have an effect on many things going on in your vehicle, especially the car exhaust system and fuel efficiency. The engine needs an exact amount of oxygen to properly and efficiently burn fuel in the combustion process. The oxygen sensor detects oxygen levels and allows the sensor to either add or reduce the fuel intake until the right balance has been reached. Ideally, there would be no oxygen in either the exhaust system or the exhaust gas. 

Tailpipe or the Exhaust Pipe

At the end of the whole process, once the exhaust gas has been filtered through and converted into more environment-friendly gasses, and after the excess noise has been eliminated, the final product has to go somewhere. The filtered-through exhaust gas and fumes have to exit the vehicle one way or the other, and it wouldn’t be very pleasant to have them simply exiting underneath your car. It would fill your cabins and the inside of your car very quickly.

That’s why car manufacturers have come up with a tailpipe or exhaust pipe to redirect the exhaust gas away from the car. The exhaust pipe comes out of the muffler at the back of the vehicle and extends out further than the length of the rear bumper, allowing it to direct the gasses away from the vehicle. These days, tailpipes come in many different shapes and sizes and are almost used as accessories and thought about as decorative features.

Modern tailpipes on a car
Tailpipes have become a car accessory

A Car Exhaust Can Be Upgraded

The car exhaust system has an effect on all other active processes in a vehicle. A quality car exhaust system can have a positive effect on the car’s overall performance, especially on fuel efficiency. That’s why a lot of car enthusiasts decide to change out their car exhaust and upgrade it. Some do it because they want to, and some do it because they have to since they have already modified their engines and made them much stronger. By increasing the diameter of your exhaust, you allow a better flow and less restriction for the exhaust gas. Another reason why people change their exhausts is simply because of aesthetics. 

How Do I Know If a Car Exhaust Is Faulty? 

Since the car exhaust system is one of the most important safety features your vehicle has to offer, you need to take good care of it and know what are the signs that there is an issue with it. Even if you don’t notice any of these signs, you should still have your car regularly checked up. 

When taking a look at your car, the mechanic won’t just change your tail light or check to see if your clutch master cylinder is bad – he will also check to see if everything is alright with your car exhaust system. So don’t worry, your mechanic will notice if there is an issue, and in the meantime, you can be on the lookout for these signs, and if you notice any of them, immediately take your car to the mechanics:

  • You can smell a strange smell coming from the exhaust, or the engine, it almost smells like rotten eggs,
  • The exhaust is chipped, broken, drags on the ground while driving, rattles, or is visibly faulty in some other way,
  • You can hear a difference in the noise of your car exhaust sounds, as they seem louder. 

The Car Exhaust System Takes Care of the Environment and Your Health

It might seem harmless, but each time you sit behind the steering wheel and fasten your seat belt to go for a drive, you produce a lot of harmful chemicals. Now just imagine if your car didn’t already have a filter for all the nasty, toxic chemicals – you wouldn’t be able to drive it for long. The exhaust system allows you to drive your car regularly without compromising your respiratory health while reducing pollution to a minimum.