Alpha Tauri AT03

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https://i.imgur.com/o8k0Qog.jpeg

Interesting. So that hole isn't for "just" driver cooling if it has a heat sink right inside of it!

As user has already mentioned, it is most likely stacks of ballast to change weight distribution.

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A nice duct that collects hot air from the discs exits & vent it / let it be sucked by the low pressure area behind those winglets.
Brake caliper has small fins like a heatsink.

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Like RB they added a gurney at the engine outlet.
AT03 cooling for Mexico race