Rear Spoilers 101: Benefits and How to Choose

Car enthusiasts often start modifying the exterior of their four-wheel investments, before remotely touching anything under the bonnet. Wheels, tyres, suspension parts, exhausts, front-end protection, and body kit pieces are some of the first parts to see a partial or complete makeover. These bring the combined benefits of improved traction, better handling, peace of mind and an aero profile to cut through oncoming air. 

While engine upgrades will get you more power, the harder part is transferring that power to the wheels. Grippier low-profile tyres, body additions like a front and rear spoiler and revised suspension layouts to stiffen up the ride go a long way when making better use of available power. And they transform any vehicle in terms of visual appeal, and standing out from the crowd of everyday, mundane cars. 

Basics of Rear Spoilers 

Car body parts like spoilers, splitters or skirts can come as standard or optional exterior packages when getting the car new. Or they’re already integrated into the design of specific models, such as the huge rear spoiler on the Subaru WRX STi, or the Porsche 911 GT3. These parts not only make a visual statement, but are there for the purpose of keeping the rear axle stable at high speed cornering, and reducing remaining lift from the car front. 

Spoilers first started appearing in race cars in the early 1970s and soon made their made way into production cars once the engineers and vehicle designer learned of their numerous advantages. The main purpose of rear spoilers is to tame or spoil remnant air that’s dispersed over the car from front-end parts including splitters, front spoilers and air dams and increase downforce acting on the rear tyres. This improves traction, allows for more stability when cornering and helps with shorter braking distances. The aim, along with other body parts, is to keep the car glued to the road. 

Benefits Spoilers Provide 

If you’re still on the edge of installing a spoiler on the roof or trunk of your car, consider the long list of benefits these parts offer: 

• Improved aerodynamics and downforce -spoilers reduce drag and push more air down. This allows cars to move more efficiently. 
• Improved stability – by cutting and dispersing oncoming air, rear spoilers keep the car stable and reduce the effect of lift or the air pressure looking to get your car airborne. 
• Increased traction – more traction or grip is the direct result of air pressure acting on the vehicle and keeping all tyres in contact with the road surface. This directly improves acceleration and braking performance. 
• Better handling – this is the combined result of more traction, increased downforce and improved stability, meaning more control at high speeds, or when cornering. There’s also less body roll, or instances of under or oversteer that affect driving lines. 
• Aesthetics – spoilers net you a car with a sportier look, provided they’re not overdone.

Other benefits are subtle, but still worth the cash. A more aero car uses less fuel, meaning engines don’t have to work as hard, or burn more fuel to reach the same speeds. Savings vary among different vehicles, averaging 1 to 2 liters of petrol for every 100 kilometres. Another overlooked advantage is reduced airborne noise. Dispersing more air away from the car means less noise reaches the cabin. The best results though are when kitting aftermarket rear spoilers with packaged body parts that also include front spoilers, splitters, side skirts and rear diffusers. 

Choosing the Right Spoiler 

Getting sizes, designs and materials right are the main factors in choosing. Key considerations are also correct placement and a professional fit. Each spoiler is designed with the characteristics of each vehicle, such as shape and length as well as, engine output, acceleration and top speeds. This means varied shapes or more pronounced sizes. Keeping sizes sane also prevents the spoiler from spoiling your ride with the opposite results. Get them too big, and you actually risk more drag, and a slower car. 

Buyers can choose between trunk, trunk lid and roofline spoilers. Designs can be generic or replicate the performance chops and look of stock spoilers in performance models, especially in hatches like the VW Golf R, the Honda Civic Type R and the above-mentioned Subie. 

Prices depend mostly on the choice of materials. Affordable options are body parts made of ABS plastic, polyurethane or fibreglass. Thermoplastics like ABS have good thermal and mechanical resistance, so perform at higher speeds and vehicles stresses (such as cornering, or hard braking), but add more weight to the car. Choose polyurethane spoilers for their durability, flexibility and increased scratch resistance if aesthetics are a key concern. Or fibreglass body kit if low weight and low cost are more important. 

Undeniably, the best results are from professionally installed carbon fibre body parts. This offers a smooth, textured look to spoilers, is the lightest yet strongest material here, adjusts to changes in air pressure better than the rest with high flexibility, and can endure extreme stresses. Go for pre-preg carbon fibre with additional materials like glass and Kevlar for the ultimate in strength and longevity. While considerably more expensive, the materials is a good match for performance and luxury cars higher up the price range.