And the slower racers are NOT required to let the faster ones to overtake just because they are faster. One defending (blocking) maneuver is allowed.
But shutting door on last second is not good manner, meaning if guy is on your side, don't ram on it, gently/slowly door closing can be done like that if opponent is
clearly behind of you and you both aren't on braking zone of corner, when entering side by side on braking zone both should keep their sides and leave living space to opponent, this normally means slower entry/mid/exit from that corner because both needs to take driving line what's not optimal for fast driving, but optimal for safe driving through corner, that's cost of fair racing.
Mutcurve is not a place where to try overtake, too high speeds to manage two cars own safe driving lines.
Flygplats can be used for overtaking, but both drivers have see this coming, and drivers behind have take caution about this overtaken on front of them, they might run corner slower so don't push too hard, you're behind and your role is watch what's happening on front of you.
Remember always, car front of you is guy who controls braking point of upcoming corner, so be careful behind, this doesn't mean at guy at front can do brake testing or on purpose brake way too early, but you have to first learn what type of braking guy on front of you is typically doing before going close on braking zone.
If you drive out, you have made mistake, don't put others to pay for it, join track safely!
If your car is damaged take really seriously how you drive it after that, again don't put others to pay your cars damage.
Even you drove out because of somebody else or break your car because someone else above still apply, problem is yours and keep it that way. Afterwards you can give all credits to guy who damaged your car etc, not excuses why you damaged others because someone first did it to you.