Tesla has obtained a patent for a system containing four electric fans inside the rear diffuser, intended to draw air from beneath the car and increase stability during braking and cornering. The patent suggests the technology may be associated with the Roadster, but it does not prove that it will be introduced in a commercial product.
The United States has granted Tesla patent US 12,746,987 B1 for a system containing four electric fans directed inside the car’s rear diffuser, intended to lower the air pressure beneath the body and increase downforce on the road, even at low speeds. The patent comes ahead of an anticipated presentation of a Roadster model on October 15, but it does not confirm that the technology will reach the production car.
Tesla filed the patent application in January 2024, based on an initial application dating to January 17, 2023. The drawings clearly show a car resembling the Model S, although the company stopped producing the Model S and Model X in April after 14 years and dedicated the Fremont line to the Optimus project, according to the source material.
How Does the System Work?
The design includes an inlet in the lower section between the rear wheels, connected to a channel that rises toward a wide outlet inside the rear diffuser. Four axial fans sit side by side, separated by three vertical fins. When activated, the fans draw air from beneath the car’s floor and expel it from the rear, creating what Tesla calls a suction zone beneath the body.
Another version of the design adds two smaller side inlets behind the main inlet. Tesla says the central inlet could draw air from behind the car rather than from beneath the floor, which would add no downforce and would waste energy. The fans can be operated by a button pressed by the driver or automatically at certain speeds, while relying on the same high-voltage battery pack that powers the car’s motors.
What Changes in Practice?
Tesla’s idea is based on the fact that conventional aerodynamic diffusers depend on the car’s speed; they may provide limited downforce at low speeds or excessive load at high speeds. The fans, according to the patent, can generate downforce that does not directly depend on the vehicle’s speed, which could improve braking stability and cornering speed in track-oriented applications.
One design feature is that Tesla says the system does not require additional components beneath the car to seal it against the road surface, such as the skirts used in some fan-car designs. This could make it easier to integrate the fans into a diffuser that appears conventional, but it does not establish how much downforce the system can generate under real-world conditions.
Possible Connection to the Roadster
This is Tesla’s second patent related to a fan car in slightly more than a year. In August 2025, the company obtained another patent using underbody fans and deployable skirts, while a more recent patent covered a concealed active rear wing capable, according to the material, of generating up to 700 kilograms of downforce, with drawings resembling the new Roadster.
Since the Roadster is the only performance car that remains in Tesla’s plans, the accumulation of these patents suggests serious interest in a track-oriented aerodynamics package. However, this is an analytical inference from the drawings and the sequence of patents, not an announcement by Tesla of the Roadster’s final specifications.
A Patent Is Not a Product
Fan-car technology is not new; the Chaparral 2J used fans in 1970, and the Brabham BT46B won the 1978 Swedish Grand Prix before being withdrawn, while Gordon Murray developed the T.50 with a rear fan. In electric cars, the McMurtry Spéirling set an outright record at the Goodwood hill climb in June 2022, and the car generates, according to the source, 2,000 kilograms of downforce while stationary, while production of the Spéirling PURE began at a price of $1.36 million.
Therefore, the main distinctive feature of Tesla’s design is placing the fans inside the diffuser without skirts to seal the car against the road, not inventing the principle itself. The patent also does not reveal a ready product or a delivery date, nor does it fully explain the details of the motors, control units, and sensors needed to manage the fans. The Roadster presentation on October 15 remains the practical test, particularly because the car was first unveiled in 2017, its dates have been postponed repeatedly, and it is now targeted for 2027 or 2028, according to the material.