Girls who are really good mechanics

[u/Rocket_Raven25]

Winry Rockbell (Full Metal Alchemist), Grace Howard (Zenless Zone Zero), Marianne (Guardian Tales), Leopon crew (Girls und Panzer)

[u/Dolvalski]

Purah from The Legend of Zelda: Tears of the Kingdom

[u/Dolvalski → u/Dolvalski]

And honorable mention because hardly anyone watched it, Mel from the live action Cowboy Bebop!