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Main Parts of a Car: The Different Car Systems & How They Relate to Each Other

Masterpiece  ·  December 23, 2021

Main Parts of a Car: The Different Car Systems & How They Relate to Each Other

Let us brush up on what you know about the parts of a car. According to Toyota, a typical automobile has about 30,000 car parts in it. 

Whether you're an everyday car owner or a passionate racing enthusiast, it’s not practical to learn about all those 30,000 parts of a car. Instead, it would be much more useful to look at a car as a sum of different systems consisting of various components working together to fulfil specific functions.

In this article, we're going to take a closer look at all the main parts and systems of a car

First, we’ll look at what goes inside the engine system, then the drivetrain, braking, electrical, and other systems that make a car work. By the time you finish reading this article, you'll probably know more about how a car works than most people do! What’s more important, you’ll begin to understand more your mechanic’s language. So, buckle up, and let's begin!

Main Car Parts & Systems

#1 Engine System

This is the part of a car where the magic happens! The car engine system is where the input (fuel and air) converts to the output (power, torque, and forward mobility). 

The process involves the mixing of fuel and air and compression of the mixture. Then, a spark ignites this pressurised mixture, creating an explosion (or 'combustion') that provides the power needed to move the car forward. 

This happens hundreds or even thousands of times per minute, and it all takes place inside the engine block, which contains all the major engine parts.

Combustion Engines

Combustion engines can be either of two types – petrol or diesel. While most cars run on petrol, the heavy-duty ones generally use diesel fuel. 

No matter what kind of car you drive, always remember to use the right type of fuel for your engine. A diesel engine won't run on petrol, and vice versa.

Fuel Injection

Whether it’s petrol or diesel that fuels your vehicle, it needs to be supplied to the engine at the right time and amount. That's where fuel injectors come into play. 

This car part has electronically-controlled valves that open and close every second, distributing petrol or diesel evenly to all cylinders. When it does its job correctly, the car can run optimally and with high fuel efficiency. 

Unfortunately, wear and tear and constant use will cause fuel injectors to get clogged, dirty, faulty, or leaky, requiring a thorough cleaning or replacement.

Types of Car Engines

Not all car engines are made the same. If you compare cars online or at the showroom, you'll see that engines are differentiated by their layout and by the number of cylinders they have. 

Different layouts allow engines to fit properly in the car body. For example, compact cars will need an engine that can fit into a smaller space under the hood.

Cars also have different needs when it comes to power and torque. These differences can be seen in the number of cylinders that the engine has. Engines with more cylinders are typically found in more expensive high-performance cars.

Placement of Engines

In most cases, cars will have their engine compartments located at the front of the vehicle. But does the engine placement make a difference? Yes, it does!

There are different reasons why a front-engine placement is standard for most passenger vehicles. Firstly, having your engine at the front of the car provides more space for the cabin, giving more comfort to passengers. 

Also, a front placement offers more traction for the front wheels and even more stability.

However, vehicles designed for fewer passengers and higher performance tend to have their engines in the middle or rear of the car. 

Middle-engine placements make an automobile more stable, which is essential if you're going at much higher speeds than usual. However, they're harder to access when those engines need to be maintained or repaired. 

Rear-engine placements are often found on racing and luxury performance vehicles. There are loads of performance benefits with this kind of arrangement, but it provides less balance.

As you can see, there is no 'perfect' engine placement. Each comes with its trade-off, depending on what the vehicle is designed for.

#2 Drivetrain System

At this point, it's clear that an engine system's primary role is to produce power. That power needs to go though many parts of the car and gets transmitted to the wheels and then onto the road to move the vehicle. 

Your car's drivetrain system does this job. Just a quick note here: a car's drivetrain plus the engine is referred to as the powertrain system.


Driving a car isn't an entirely monotonous process between your starting point and the destination. Sometimes during your drive, you'll want more speed. Or depending on the terrain, you may need more power, like when you're driving uphill. The part of a car that serves this purpose is the transmission system so it can switch between the appropriate gears to suit changing driving conditions.

Generally, transmission systems come in automatic or manual form. With manual transmissions, you'll change gears yourself depending on what you need, while an automatic transmission does it for you. 

With modern driving technology, other kinds of automatic and manual transmissions have also been developed, like powershift transmissions and CVT transmissions (which we'll discuss in a while).


Cars with manual transmissions have parts called clutches. The clutch works between the shaft coming from the engine and the one that's connected to the wheels. 

A clutch engages and disengages the power transmission between those two shafts. So, even though the shaft from the engine is always rotating, it won't necessarily turn the car's wheels unless the clutch allows it.


In some cases, car manufacturers prefer to use CVTs or Continuously Variable Transmissions instead. These are sometimes called 'shiftless transmissions'. 

You see, conventional transmissions go from one gear to the next (e.g., first gear, second gear, and so on), with each gear representing a specific gear ratio. A CVT doesn't move from one gear to another this way. Instead, it moves between different gear ratios gradually. 

To use a colour metaphor: conventional transmissions move from black to white, while CVTs move across greys.


Next in line are the differentials. This car part is designed to transfer torque from the engine's drivetrain to the wheels. Just like many parts of a car, differentials come in different forms. 

There's the open, locking, torque vectoring, and welded/spool differentials, not to mention the Limited Slip Differential (LSD). The difference? Each type is built to suit different applications. 

For instance, the Limited Slip Differential (LSD) is usually found on racing and high-performance cars because of its ability to avoid slipping. This is crucial when you're racing at breakneck speeds!

#3 Braking System

So far, we've looked at the engine and powertrain systems which generate and transfer power for the car to move forward. An equally important part of a car is the braking system which slows down and brings cars to a halt. 

How Brakes Work

Braking systems are relatively simple: they generate friction which opposes the car's movement, gradually reducing its speed whenever the driver presses on the brake pedal. 

This whole process converts the mechanical energy (while the vehicle is moving) to heat (generated by the friction used to slow it down).

This process causes a lot of wear and tear on certain brake parts, which is why it's essential to maintain your brake system regularly. In this part of the car, one of the most replaced parts is the brake pads which is where the friction takes place. 

Even though the outcome is the same, brake systems also come in different forms, like drum brakes and disk brakes.

Master Cylinders and Combination Valves

Master cylinders and combination valves are essential parts of the entire brake system. When the driver presses down on the brake pedal, the master cylinders and combination valves help to convert that energy into hydraulic pressure. These parts also distribute that hydraulic pressure to all of the car's wheels simultaneously.

Anti-Lock Brakes and Power Brakes

Many modern cars come with ABS or anti-lock braking systems and power brakes as standard features. These aren't really 'types' of brakes per se, they're just additional parts that make braking more efficient. 

The ABS ensures that your car's tyres don't lock up entirely while hard-braking, which prevents the vehicle from slipping and losing control. Power brakes, on the other hand, amplify the amount of force being applied to the brake pedal.

#4 Steering, Suspension, and Tyres

At this point, we've looked at the systems that get the car moving and that slow it down to a standstill. Now, let's look at the parts of a car that are mostly used when it is in motion. These are the steering, suspension, and tyres of the car.

How Steering Works

Steering is crucial to control the direction in which the car moves. When it comes to the types of steering systems used today, very few vehicles, if at all, still use the traditional manual type. Manual steering can be very tiring for the driver, especially on longer drives and on heavier vehicles. 

Thankfully, we now have hydraulic power steering and electric power steering systems, which multiply the turning force applied by the driver on the steering wheel, making steering less physically demanding.

Suspension Systems

No matter what direction a car is heading in, the ride would be very bumpy if the wheels were attached directly to the car's body. This is because any shocks and vibrations from the wheels would be felt throughout the vehicle, making the entire trip very uncomfortable and potentially damaging in the long run. 

For this reason, modern cars have suspension systems. 

Aside from the tyres, the suspension systems also consist of shock absorbers, springs, and rods that attach the wheels to the vehicle. The system does two things. 

First, it ensures that there's maximum contact between the wheels and the road. Also, it absorbs any of those shocks and vibrations mentioned earlier. This makes the drive much more comfortable while protecting cargo and other parts of the car

Generally, suspension systems fall into three categories: independent, dependent, and semi-independent. The difference? On independent types, what happens on one wheel doesn't affect any other, while on dependent suspensions, the movement of a tyre affects the rest. 

These differences will matter according to where the vehicle is being driven and on what type of terrain. 


Tyres are literally 'where the rubber meets the road'. They work by rotating and gripping the road, generating friction that moves the car forward. 

Tyres will function their best when they are filled with the right amount of air. Usually, drivers check their tyre air pressure manually at their nearest petrol station. 

Tyre pressure sensors are also becoming a common feature these days. Some come as a standard feature on newer cars, but there are plenty of aftermarket options available as well. 

#5 Electrical System

Cars don't just rely on mechanical auto parts; they also depend on electrical systems. These two systems are highly interdependent, and in modern cars, it's almost impossible for one to function without the other.


At the heart of the electrical system is thebattery. This is where electrical power is stored before being distributed to the rest of the car. Without a functioning battery, the ignition system would not function, and the car won't be able to start at all.

Ignition System

When you turn the key in the ignition, this system takes power from the battery and uses it to create a spark in the engine's spark plugs. This is the first step in the combustion process, where the engine burns fuel and air to generate power. With a faulty ignition, the car won't start at all.

Fuses & Connectors

Just like any electrical system, the one in a car relies on fuses and connectors. Fuses offer protection by ensuring that power surges don't damage any electrical parts. Connectors and wiring, on the other hand, conduct electrical power from the battery directly to car parts like lights or even onboardcar computers.

Car Computers

In recent years, there's been an increase in the usage of car computers. In this context, we're not referring to any computer system that provides information or entertainment to the driver or passengers. Instead, we're referring to the computers regulating the car's performance.

Examples of these computer systems are the Power Control Module (PCM), Engine Control Module (ECM), Transmission Control Module (TCM), and the car's immobiliser. The Power Control Module (PCM) is the brain of the vehicle, coordinating the functions of various parts and systems of a car. If the vehicle is ever stolen, an immobiliser can be activated remotely to shut the entire vehicle down. 

Windshield Wipers

The car's electrical system also powers a lot of smaller motors used throughout the vehicle, such as window motors and even the ones that move your windshield wipers

#6 Exhaust System

Earlier in this article, we've mentioned that combustion engines take in air and fuel to burn for power. Now, we're looking at what comes out on the other side of that process through the automotive exhaust system. 

Aside from power, the combustion engine also produces two things: exhaust gases and noise. 

These gases are toxic to humans and damaging to the environment. At the same time, the loud noise is a significant nuisance to everyone near the vehicle, which is why governments have laws regulating these two byproducts generated by cars.

Cars manage these byproducts with exhaust systems which reduce exhaust gases and noise and expel gases out of the engine cylinders and the vehicle safely. As part of the process, it also reduces harmful emissions and noise with catalytic converters and mufflers.

Catalytic Converters

In an automotive exhaust system, catalytic converters take toxic gases, like carbon monoxide, nitrous oxides, and hydrocarbons, and then converts them into harmless water and carbon dioxide.


Mufflers work by allowing exhaust sounds to bounce around inside of them. As sound waves bounce off surfaces, they gradually weaken to acceptable levels. By the time those sound waves make it out of the tailpipe, they'll be just a soft hum.

#7 Other Supporting Systems

Finally, let's take a quick look at a few supporting parts of a car that help you drive safely and comfortably.


On a car's instrument panel (behind the steering wheel), there's a bunch of displays including a few meters. One of them is the odometer, which is specifically for measuring the distance travelled by the vehicle.

The odometer is useful for two reasons. Firstly, it measures the total mileage of a car throughout its lifetime, giving you a good sense of how much wear and tear a vehicle has, especially if you're buying it second-hand. The counter that shows this total distance cannot be reset or altered by anyone, even a mechanic.

The odometer also has a secondary counter, sometimes called a trip counter, that you use to calculate the distance on a specific trip. This counter can be reset back to zero whenever you want to start measuring again.

Automotive Cooling Systems

The combustion engine and other parts of a car under the hood tend to get very hot. This is normal, and it's alright as long as nothing overheats. Cars have an automotive cooling system to prevent them from overheating. 

It consists of a water pump, thermostat, radiator, fan, and other smaller parts. The system circulates coolant through the inside of the engine to absorb heat. Then, the coolant moves through the radiator where the heat is released into the environment.

Auto Body Panels

Imagine a house with pillars but no doors, walls, or even a roof. Technically, it's still a house, but there's little or no point to it. Cars are the same. 

A vehicle with a frame and all the systems mentioned above can still get you to your destination. However, you'll receive no comfort and almost no protection without the auto body panels.

These panels are the parts of a car that protect you from the elements, keep you safely enclosed, and make you travel comfortably. 


As a car owner, you don't have to be an expert or a 'car guy' to appreciate the systems mentioned in this article. However, your life would be a lot easier if you did have a basic understanding about the different parts and systems of a car and how they work together. 

Knowing the systems also helps you relate one car part to another and comprehend how a failing radiator can cause an engine to overheat or be damaged. 

At the very least, having this knowledge will make it much easier for you to ‘car-speak’ with your mechanic whenever he starts talking about which parts of the car need servicing or repair. Learn more from, and you may also search for replacement parts through our Car Part Finder.

By Ray Hasbollah

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