I am on season 3 my team nearly fully upgraded the car and it's still the slowest in grid even when the AI haven't done many upgrades, it seems like the ceiling for performance on the car is ridiculously low compared to AI.
Not sure if this is how it was intended. I have highly rated drivers and they are barely getting to P15. It seems like the upgrades aren't doing anything and it's just staying as it was beginning of the game.