I've notcied that the AI, after running a bunch of laps in practice/test day pit, exit to garage then just sit there in 1st gear, sometimes they come back out, sometimes they don't. The combined engine sound is deafening as one by one the AI pit. I also notcied that the AI that are just sitting in the garage have their brakes applied 100% while sat in the pits. I'm not sure if this is a bug or not, just thought it was strange.
Big necro, but the AI can indeed be deafening in the pits. Perhaps the sound also echo's louder cause of the walls, but not sure if the game-enige supports that.