It makes a car more efficient and faster.
Honda recently filed a patent with the United States Patent and Trademark Office for a deployable side skirt. According to Honda's patent filing, there is a need for a system that "improves the aerodynamic performance of a vehicle without detracting from the outer appearance of the vehicle while stopped or operating at lower speeds."
As you can see from the patent images, two deployable panels are stowed within the sidewall of the vehicle when not in use. These are deployed at speed to reduce the amount of air that makes contact with the tire. In doing so, it creates a pressure difference between the forward and rear faces of the tire, improving the aerodynamic flow.
As demonstrated, the system consists of a first side panel joined to a second side panel along a tapered front edge.
Because the patent is clearly meant for a road car, having the side skirt permanently fixed is a no-go. According to Honda, it also spoils the look. Instead of having a permanent side skirt, this system will measure various details via sensors and deploy as far as possible when the time is right. Like when you're doing 75 mph down a flat highway, for example. You'll be hypermiling like a boss.
The skirts also have the ability to change the angle of the airflow, so they won't always sit flush with the tire. The reason behind this is underbody flow, which is chaotic at best underneath a regular road car. It creates enormous drag as the air flows underneath the car and struggles to pass by various components and the tires.
We admire the aerodynamic efficiency and the claims that it will result in a less chaotic flow, but Honda is borrowing a bit of F1 technology here. We're talking specifically about ground effect, which was discovered by accident by a Lotus engineer.
Lotus had a similar system, though not as advanced as Honda's. In short, the air outside the car flows at normal speeds creating a high-pressure zone. The air forced underneath the car flows much faster, creating a low-pressure area. Controlling these pressures is key to reducing aerodynamic drag and, according to the patent, "can be advantageous in achieving enhanced vehicle performance."
Yep, Honda, we're pretty sure it can. Perhaps even enough to reclaim a lost record. In 2017, the Honda Civic Type R set the Nurburgring record for the fastest front-wheel-drive production car with a time of 7:43.80.
The title was then grabbed by Renault's ridiculously overpriced Megane RS Trophy-R, which set a time of 7:40.1. Technically, the fastest FWD car is the Lynk & Co 03 Cyan concept. Still, we're ignoring it because it's not a production car.
There has always been this belief that there's only so much power you can send through the front wheels, and Honda will likely be right on the cusp of it when the recently leaked Type R makes its debut. So the secret to setting a new record is not power but weight and aerodynamics.
We can see the benefit on the average ICE car or EV, but we can just as easily see how Honda could build an even more hardcore Civic with a system like this. It bought Lotus a second per lap around its short test track, and while a road car can by no means be compared to an F1 car, we wonder how many seconds per lap this system can save around the Green Hell?