In real life races, it sometimes happens that, making a late call to the pits, the pit crew isn't ready yet and the car needs to wait some seconds until everything is 100% ready. So, I would implement that mechanic to the game. Let's say that the pit crew preparing time is 20 seconds. If you call your car to pits, there would appear a time bar filling as the pit crew is being prepared. If you make the call to late, the car would have to wait until that bar fills up to 100%. As the pit crew is better, the preparing time would be shorter, and so on.
#Pit crew preparing time
wild vector
kindred star
gud idea