"Meaningful" on order of 100lbs at 60mph. Which isn't nothing, but a Viper ACR has a peak downforce of 2000lbs@177MPH, or basically half the total weight of the car.

Plus, with extreme aero, there's a top-speed vs downforce tradeoff to be made. The big fan trick doesn't have that issue.

If you drill into published specs for wings, it's generally true they only really start to work at silly speeds on most road legal cars. The far more important effect is upon the emotional response of the owner when they look at it... There are exceptions, but virtually all rear spoilers only start to do their work meaningfully at well over 100mph.

Example: Porche Cayman GT4 RS, extremely potent track-day Porche with giant wing.

> https://newsroom.porsche.com/en/press-kits/718-spyder-cayman...

> "At the car’s maximum speed, there is a total of 122 kg of rear downforce."

Yes, thats right, you get 122kg of extra downforce once you hit 196mph. Really helpful in 2nd gear... The reason manufacturers generally only quote wing downforce on road cars at incredible speeds is because the number is not very impressive at lower ones.

> Example: Porche Cayman GT4 RS

That's a street car. You need to look at race cars to see where wing development can go.

For an example of race cars which generate downforce at autocross speeds, take a look at cars like https://www.autoxandtrack.com/a-mod-acme-special-fastest-aut...

that's a street car though. what about actual GT3 cup cars or GTD class cars?

i couldn't find any numbers, but they do put them in the wind tunnel.