What Are Car Parts Aero? Features Of Each Part & How To Attach

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You may have seen the term “aero” at car accessory stores, but have you ever wondered which specific part of a car it refers to?

A simple example of what an aero part looks like is a feather-like part attached to the trunk. This is a type of aero part and is called a “wing.

This page explains the effects that aero parts have, the name of each installation location, and how to install them.

In addition, we will also introduce the vehicle inspection regulations for aero parts.

What Are Car Parts Aero?

Aero is an aerodynamic part attached to a car. Examples include bumpers and spoilers attached to the trunk.

Aero” is often abbreviated to “aero”, but the correct term is “aero parts”, or “Aero Parts” in English.

In our daily lives, we may not be so concerned about aerodynamic drag, but a car is a vehicle that can reach speeds of nearly 100 km/h on the highway.

Having air on your side has more benefits than you can imagine, such as improving fuel efficiency by allowing air to flow cleanly and stabilizing the car by holding it down with the force of the air.

Aero parts are one of the most important parts in today’s car situation, where the emphasis is on lower fuel consumption.

Did Aero Become Popular In The 1980s And 1990s?

Aero parts were popular in the 1980s and 1990s, but in recent years, the number of cars retrofitted with aero parts has been decreasing year by year.

At that time, many cars had a subdued design, and in their normal state, they were, at worst, wild.

Therefore, many users were attracted to the gap between the two, as they could create a sporty atmosphere at once by installing external wheels and aero parts.

In other words, the main purpose of installing aero parts at that time was to dress up the car rather than for aerodynamic reasons.

In fact, it was not uncommon to find aerodynamic parts that increased aerodynamic drag, except for those that were genuine aero parts of the manufacturer.

However, the dress-up boom eventually faded away, and the trend shifted to eco-cars.

Many eco-cars were originally designed to reduce aerodynamic drag to the utmost limit. Therefore, installing aero parts may worsen fuel efficiency.

In addition, many users who drive eco-cars place importance on the economy, to begin with, and the number of people who “do not want to spend unnecessary costs on aero parts” has increased, so the majority of vehicles now come with normal aero parts.

Other reasons for the decrease in the retrofitting of aero parts include the following.

  • Aero parts are installed as standard equipment.
  • Increased number of vehicles are difficult to install aero parts due to problems with sensors attached to bumpers, etc.

There Are Two Main Types Of Aero Parts

Aero parts are originally designed to reduce aerodynamic drag, but they also bring a dress-up effect because they change the appearance of the vehicle. Therefore, there are two main types of aero parts.

Aero Parts For Racing

These are aero parts designed with an emphasis on aerodynamic performance, which is their original purpose.

Racing cars have completely different shapes from ordinary passenger cars, such as wide fenders, huge GT wings, and complex front bumpers.

These aero parts for racing are installed in order to make the air your friend, as they are originally intended to do.

Aerodynamic aero parts are sold not only for racing cars but also for ordinary passenger cars. When installed, they have effects such as improved stability at high speeds, which can be felt especially when driving on highways.

They are also recommended for those who participate in driving competitions at circuits.

For Dress-Up

These are aero parts that emphasize appearance rather than performance. Compared to racing aero parts, there are a variety of designs available, so this type is recommended for those who want to pursue their own design preferences.

However, some aero parts may reduce fuel efficiency or aerodynamic characteristics, so please examine your choice carefully.

What Are The Effects Of Aero Parts? Are There Any Benefits To Daily Driving?

We have already mentioned the effects of aero parts, but there are many other benefits in addition to those mentioned above. Let’s take a look at the four main benefits of aero parts.

Benefit 1: You Can Customize The Style To Your Liking

The combination of aero parts allows you to create a style that you like.

It is no exaggeration to say that most of the users who install aero parts on their cars do so for the purpose of dressing up their cars. By installing aero parts, you can fulfill such wishes as “to achieve a dynamic look” or “to add volume to the underbody.

The aero parts that can make a big difference in appearance are as follows.

  • Front spoiler
  • Rear spoiler
  • Side steps
  • Rear wing

Effect 2: Reduce Aerodynamic Drag At High Speeds

One of the major purposes of installing aero parts is to “reduce aerodynamic drag. The standard installation of aero parts on recent passenger cars is also intended to reduce aerodynamic drag and improve fuel efficiency.

Since aerodynamic drag increases in proportion to the square of the speed, the effect may not be noticeable at low speeds, but it becomes apparent when the speed exceeds 80 km/h.

Even if the effect is low in the city, where there is a lot of stop-and-go traffic, those who frequently drive on highways will be able to enjoy the benefits of reduced aerodynamic drag.

Effect 3: Downforce Improves Handling Stability

Downforce refers to the force that pushes a car downward, improving handling stability by holding the car to the ground.

Since the tires are pressed down and friction is increased, the grip is increased, and cornering speed is improved. Racing cars are equipped with aero parts because they want to generate downforce.

Effect 4: Vehicle Weight Can Be Reduced By Replacing Parts

The last effect is weight reduction through parts replacement. While adding aero parts such as wings will increase the weight, this effect can be obtained by replacing the originally installed parts with lighter ones.

For example, the hood could be replaced with a carbon aero hood.

Where To Put Aero Parts?

Aero parts have different effects and names depending on where they are installed on the car. The following is an explanation of the installation areas and their effects.

The Lower Part Of The Bumper: Front Spoiler

Aero parts installed on the lower part of the bumper, the part where the car first touches the air, is called “front spoilers. There are bumper-integrated spoilers and “lip spoilers” that are retrofitted to the lower part of the bumper.

The effect of the front spoiler is to reduce the front lift by lowering the pressure of air entering under the floor. However, when combined with a diffuser (described below) to create downforce, the type that draws more air under the floor may be better.

The Lower Part Of The Left And Right Doors: Side Steps

Aero parts installed under the left and right doors are called “side steps (side skirts). Side steps prevent air from entering under the floor from the sides of the body and serve to rectify the air under the floor.

This allows air to flow cleanly backward, reducing air resistance and gaining downforce at the same time. It is also a part that has a dress-up effect, as the space between the lower part of the body and the ground appears closer.

Rear Bumper: Rear Under Spoiler

Aero parts attached to the rear bumper are called “rear under spoilers” and have the effect of preventing air from stagnating behind the vehicle. This is very important to improve fuel economy because air stagnation causes the parachute effect, which increases air resistance.

It is often combined with the following diffusers, in which case downforce is further increased.

The Lower Rear End Of The Vehicle: Diffuser

The “diffuser” attached to the rear end of the rear bumper is shaped like a row of vertical fins on a bottom surface that is lifted up at an angle.

This shape allows air to be extracted even faster and generates negative pressure. In other words, it has the effect of sucking the car to the ground. Furthermore, if combined well with the front spoiler and side steps, a larger negative pressure can be generated.

Rectifying the air under the floor to generate negative pressure is called the “ground effect,” and the advantage of this is that downforce can be obtained without creating air resistance.

Because it provides stability without sacrificing fuel economy, more and more cars in recent years are equipped with diffusers as standard equipment.

Upper Trunk Lid: Rear Wing

The most conspicuous aero part is the “rear wing” installed above the trunk lid. It has the same effect as the “rear spoiler” described below, but this one is shaped like a plate and has a greater effect.

The rear wing is shaped like an inverted airplane wing, so it generates downforce instead of lift like an airplane. It has the advantage of being more effective than other parts of the body and can be effective even at relatively low speeds.

However, the downforce obtained from the rear wing is not a ground effect, so there is a trade-off with aerodynamic drag. If too much downforce is pursued unnecessarily, fuel consumption may worsen, so it must be set up properly.

Trunk And Rear Gate: Rear Spoiler

The “rear spoiler” is installed on the trunk and rear gate. Although it is smaller than the wing, it is effective in generating downforce.

Although it generates less downforce than a wing, it is suitable for passenger cars because of its lower aerodynamic drag. There are many rear spoilers that come as factory-installed equipment.

Points To Keep In Mind When Purchasing Aero Parts

When actually purchasing aero parts, there are a few points to keep in mind. Check them beforehand so that you will not regret your purchase.

Are They Painted In The Same Color As The Car Body?

If you purchase unpainted aero parts, you will be charged separately for painting. Aero parts painted in the factory body color from the beginning are also available and are recommended.

However, not all of them are available in the factory colors, so please check in advance.

Are The Parts Made By A Genuine Manufacturer?

Some external aero parts may rub on bumps if the ride height is not raised as a result of prioritizing design. If you raise the ride height, the dress-up effect will be lost.

Aero parts made by genuine manufacturers are designed so that they do not interfere with driving, so if you are worried about problems after installation, we recommend that you use genuine aero parts.

Is It A Material With A High Degree Of Freedom In Modeling?

Most aero parts are made of FRP, but some are made of urethane or ABS resin. Urethane and ABS resin parts have high precision, but they are difficult to repair when damaged.

Although FRP is not necessarily superior, we recommend FRP aero parts with a high degree of freedom in modeling if there is a possibility of repair, such as “I am focusing on the design, so I might scrape the underside of the car.

How To Attach Aero Parts

As a precondition, aero parts rarely fit perfectly without any modification, even if they are exclusive to a particular car model. There is inevitably some error in the product, so detailed matching work is necessary.

In this section, we will introduce the installation process when installing aero parts by yourself and when hiring a contractor.

Do-It-Yourself Installation

When installing by yourself, you will need to do some processing to adjust to the product error.

  • Phillips screwdriver
  • Electric drill
  • Steel screws (screws)
  • Masking tape
  • Sandpaper (#80)

Once the tools are prepared, it is time to start the processing work. Although there are differences depending on the car model and parts, we will use the front spoiler (lip spoiler) as an example.

  1. Jack up the car to make it easier to work on and secure it using a rigid rack (commonly known as a “Uma”).
  2. Protect the bumper with masking tape first to prevent scratches.
  3. Temporarily attach the spoiler, which is difficult to do by one person, so two people are recommended.
  4. Mark the surface where the spoiler will hit the bumper and use sandpaper to cut the gaps to match.
  5. After painting, fasten screws where necessary.
  6. Remove the masking tape to prevent scratches, lower the jack, and the work is complete.

When Hiring A Contractor

When hiring a contractor, you may first consider bringing your car to a dealer or car accessory store, but these companies may not be able to handle the installation of aero parts that you bring in.

However, these companies may not be able to handle the installation of aero parts that you bring in. If they can handle it, there is no problem, but it may be a hassle to contact multiple companies.


In this issue, we have explained the effects of aero parts and the characteristics of each part.

Although the number of users who retrofit aero parts has been decreasing because recent cars are equipped with aero parts as standard equipment, it is still valuable customization for those who pursue their own personal style.

When purchasing aero parts, it is recommended that they be the same color as the body and made by a genuine manufacturer. If you are particular, you may paint and install external parts.

Please enjoy your original customization within the safe range in accordance with the safety standards.