I'd like to know this as well. While we're at it, which value determines if a B-Spec driver is shared or not? I have 2 or 3 drivers stuck and can't use them. Did you find anything since you posted? I guess we have to determine the rough location and go from there with trial and error?
EDIT: Found the
You must login or register to view this content. for drivers. Look for the first coloured value, 52 55 for not shared. Maybe you're able to find the same values for cars.