Purpose / meaning of the rear spoiler in motorsport & tuning!

Reading time 6 Min.

Recently updated on May 16, 2023 at 03:20 p.m

The rear spoiler is a necessity in motorsport and a must-have in tuning circles. But in real life the saying often applies: Form follows function! Rear spoilers that are really high, is that a must? Above a certain size, everything that contributes negatively to the harmonious body shape of sports cars is just embarrassing. Especially since the intended function of the rear spoiler is hardly noticeable at traffic speeds. However, the additional downforce of the rear spoiler cannot be avoided if you want to be successful on racetracks. In practice, however, the disadvantages outweigh the advantages.

What is it for rear spoiler?

The rear spoiler on a "normal“ Street cars often have purely aesthetic functions. As a result, the slim body shape is slightly stretched and lengthened to the rear. It is usually already installed as standard or is installed on the body with sporty additional equipment.

The rear spoiler is an indispensable tuning part for high-performance automobiles at high speeds. At high speeds, it increases the vehicle's downforce and improves its stability. This effect increases with speed, primarily in corners. In racing, in addition to the rear spoiler, Front– and partly too wheel spoiler used to increase cornering speed. In order to keep the vehicles on the road at high speeds, sports cars such as Porsche or Lamborghini, including production models, sometimes have huge ones rear spoiler, which even extend automatically depending on the speed. Depending on the manufacturer, the driver usually has no influence on this.

However, the increased downforce only really becomes noticeable at speeds between 100 and 150 kilometers per hour. For the most part, you don't notice it on the freeway or in city traffic. With normal, everyday cars, there is little risk of them lifting off the road, because this would require speeds of well over 250 km/h necessary. Vehicles that reach such speed ranges ex works without a rear spoiler are also designed for this by the manufacturer. That is why oversized spoilers, especially retrofitted ones, are mostly just decoration in normal traffic, without any functional value.

The arguments for not having a rear spoiler!

Tuners often add extra fat rear spoilers to make the vehicle appear strong. Most of the time, however, these do not have the desired effect, since the vehicle's aerodynamics are already well balanced during development. Therefore, the aerodynamics can be significantly affected by an additional attachment. A rear spoiler increases the air turbulence behind the car, which often increases air resistance and the drag coefficient increased, even if this may increase the downforce and stability (measure of aerodynamic slippage) somewhat. In principle, retrofitting can result in higher fuel consumption and louder wind noise.

A perfectly tuned rear spoiler should therefore have the smallest possible frontal area and smooth shapes so that the aerodynamics are not negatively affected. And the extra weight can also be an important factor. A rear spoiler is therefore only advisable if, in addition to improving the vehicle's appearance, it also reduces drag and downforce. Also bear in mind that rear spoilers, which protrude from the bodywork and are only connected to it in two places, can become detached during the car wash, for example. Then only the time-consuming remains Hand wash!

How is a rear spoiler installed?

The spoiler is usually attached to the rear of the vehicle with screws or glue. At low weight, such as a small spoiler, the attachment is often sufficient even with double-sided adhesive tape. Incidentally, it is worth visiting a specialist workshop if the rear spoiler has to be screwed on tightly. They know how to attach the rear spoiler correctly and how to remove it again if necessary.

However, this almost always results in damage to the vehicle paintwork and, if necessary, to the bodywork. This can be a challenge when restoring the car to its original condition, for example for sale or to eliminate wind noise caused by the spoiler. It is therefore important to think carefully about the installation of the rear spoiler.

What is the price of a rear spoiler?

The variety of materials, shapes and colors is huge, as is the price range. A universal part usually starts well under €100, while an adjustable carbon version can cost several thousand euros. Various giant parts of golf and Co. are unflatteringly described in Germany as "Fries counter" designated. Our advice: Less is often more! And ultimately, the vehicle also decides on the choice of rear spoiler. No one should fit a €100 plastic part to a Porsche 911 Turbo for well over €200.000.

Tip: Depending on the type, the edge protection must be observed!

All spoilers, including the rear spoiler, usually have to be approved and registered. If it protrudes in height and width over the vehicle, then the Registration usually difficult, but not entirely impossible! In any case, documents (ABE, Teilegutachten, E-mark etc.) must be available for the spoiler so that it can be used legally on the road.

Which rear spoilers are allowed?

• Anything that does not impair traffic and operational safety. In doing so, primary attention must be paid to splinter protection and sharp and possibly protruding outer edges. Spoilers that exceed the width of the vehicle are generally only permitted in racing. Nevertheless, in case of doubt, the test center decides whether a spoiler endangers operational and road safety or not. Retrofit parts with an EU type approval can generally be used legally.

What is most important for security?

• From the point of view of pedestrian protection, rear spoilers should not be made of hard, splintering materials or have sharp edges. In the worst case, such a spoiler can lead to the car being immobilized.

What is the benefit of a rear spoiler?

• If you only drive your car in normal traffic and not on a race track, you will hardly notice any change in downforce. This only happens at high cornering speeds of at least 150 km/h.

Of course, that wasn't the end of it!

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