Carbon Fiber Rear Wing for a 2014 Toyota Prius (Feb 2026 - Aug 2026)

I engineered a carbon fiber rear wing for my 2014 Toyota Prius.

It is predicted to produce approximately 422 N of downforce at 80 mph, designed around a Selig S1223 airfoil at a 10 degree AoA. Drag added from the wing is predicted to be approximately 84 N at 80 mph.

Features:

• CD = 0.391

• CL = -0.584

• L/D = -1.49

• 2 layers of plain weave carbon fiber hand laid over a high density XPS foam core in the shape of a Selig S1223.

• Machined aluminum endplates on either side to reduce tip vortices and to keep the pressure differential.

• Waterjetted 6061-T6 swan uprights.

• Total weight: 5.5 lb

• Airfoil: Selig S1223

• Composite: 2 layers of carbon fiber, wet layup, air cured

• Endplates & uprights: 6061-T6 aluminum

• All the aerodynamic values are predictions based on my CFD meshing and simulation. I am not a CFD expert, ... yet.

• FEA simulations using Siemens NASTRAN FEA.

• Engineering Design Process under all these images.

Everything designed and assembled in Fusion 360

CFD pressure pathlines over the wing display an expected high pressure above and low pressure below, creating a pressure differential that promotes downforce. Wing tip vortices are controlled as expected with the installed endplates. All done in a watertight workflow using ANSYS Fluent 2026 R1. This is my first experience with CFD and I am excited to use this tool for future projects.

FEA validated a 2x factor of safety, safe in all regards and can withstand the predicted downforce.

Miscellaneous Photos

The Engineering Design Process:
This project started in February 2026, where I used Fusion 360 to start playing around with airfoil shapes and the possibility of creating a wing for my car. I used an airfoil coordinate import function to get the exact shape in CAD, then extruded to the desired width of 44". The endplates and swan neck mounts went through many iterations. The reason for the swan neck is that it is notoriously known for allowing more downforce since it does not affect the low pressure region of the wing. Traditional mounts mount directly under the wing, creating separation layers which directly harm the underside suction, critical for producing downforce. The endplates were designed for me to learn 3 axis milling. I could have easily waterjetted these parts and been done in a few hours, but I chose the 3 axis CNC to learn Mastercam and milling. I choose projects that allow me to learn more than what I already know. The swan necks were waterjetted.

The main wing was created using a high density foam core with two layers of plain weave carbon fiber, hand laid and air cured. The reason for two layers was because this car will not be experiencing anything further than a two-layer strength and stiffness. It is estimated to produce ~422N of downforce @ 80 mph, and the Prius can barely get to 90 mph, and that is with some elbow grease. Three or four layers would be appropriate for a sports car that experiences higher speeds and cornering. The plain weave was used because it is sturdy enough for the straights that it will go through. If I were to actually track this car, I would rebuild with four layers and including 45 degree layers. My car is a daily and will mainly be experience low speed straights. Also, budget is always an engineering limitation; these options were budget friendly.

The biggest challenge was the mounts that actually connect to the car. Since I did not have a 3d scan of the rear, I had to make educated guesses on how to line up and attach the mounts so the wing is straight. Using methods such as taking photos, inserting them into cad, and creating the model based on that. Using my phone as an angle measurement to design according to the angle of the back of the car. A ton of 3d printed iterations of the mount to get the thing working. It was the most challenging part and when I go back to make V2 of this wing, the first thing I will do is 3D scan the rear of the car to accurately design mounts. This way, everything can be assembled in CAD with minimal 3d prints. In any case, the 3d printing allowed for a cheap iterative solution.

As a manufacturing decision, I ended up going with PETG mounts on the car. This saved me time and money, and after driving the car on the roads at 80 mph and some turning of the car, those mounts were not going anywhere. Aluminum is the wrong material for the endplates, and I know that; it was purely a decision so I can learn machining. Carbon fiber endplates are the correct choice and are way easier to fabricate and weigh a ton less. The swan neck wings are 6061 and those were the right manufacturing process and material. 

The downforce equation was employed, and on paper I got an estimated 392 N of downforce; comparing that to the CFD predictions of 422 N that is a 7.37% difference, which is quite close considering the downforce equation uses the surface area of a rectangle to calculate and doesn't assume an airfoil shape. And it uses a Cl from airfoiltools, which is not really accurate (mainly a reference value).