The following is from
another forum -ukgpl.com. Same message, with pictures.
Corner Rights
If you watch the odd few GPL drivers in action you might think the rule for corner rights goes something like, " Whatever piece of ground I can barge my way into I have the right to ". Well, ... not so. There is actually an etiquette for corner rights. It's not just for GPL, or racing sims, but is basically the same for every level of real-world motor racing - from Formula Ford to Formula 1 and everything in between. " What ! ", you say. " You mean I don't have the right to throw my car into any gap I see ? ". Actually no, you don't - and if you raced in any real-world competition the way you may race in GPL, instead of being hailed as a motor racing genius you may find yourself banned from even the lowest levels of the sport. Some of the everyday things you see in GPL simply aren't tolerated where real cars are damaged, real money is the cost of repair, and real lives are at risk.
In brief, the concept is, you must establish substantial overlap with the car ahead before a corner's turn-in point to have the right for room to be left for you by the ahead driver. Substantial overlap means at least that the front of your car is up to say the driver's position in the ahead car - and that's at the very least. You probably should have more in many circumstances. The ahead driver has ever right to be fully committed to the racing line of his choice without any interference if there was no overlap before he turned in.
If sufficient overlap is established before the turn-in point, then the behind driver has the right to room. The ahead driver can still battle for the place of course but must do so from a wider-out position, leaving room for the behind driver.
You can see here why overlap established after the turn-in point isn't really valid and therefore isn't honored in car racing rules. Its actually false overlap that's created by the turning movements of the cars. Its not due to one being faster than the other or one out-braking the other. In positions 1, 2, and 3, below, you can see that the Lotus has no overlap at all if you consider the straight ahead direction - shown by the blue lines. But if you take a perpendicular from the attitude of the cars, shown by the red lines, there is some overlap at position 2 and substantial overlap at position 3. This overlap is entirely false of course as the Lotus here hasn't actually out-braked or out-sped the Eagle by any amount what-so-ever - as I hope you can see form this diagram. Unfortunately many drivers think that if they do this they are some kind of out-braking genius, when in fact they are not out-preforming the other driver at all. Its a geometric illusion that has nothing to do with a driver's ability or performance. If they could really out-brake the other, they would have made some overlap before the turn-in point, not after it.
1 Before the turn-in point there's no overlap - therefore the Lotus has no right to room or to interfere with the Eagle's normal racing line in any way.
2 But, as often happens, the Lotus sees this empty zone along the inside and thinks they can zoom up into it,
probably believing this to be the move of a talented racing genius.
3 Its possible to get apparent overlap after the turn-in point. The point is you shouldn't.
4 The Lotus may actually achieve their objective, forcing the Eagle out wide, who may actually not press the issue for the sake of not crashing - if they can.
5 But, if the Eagle doesn't back away, and holds their line, as they're entitled to do, this is what happens as often as not.
The issue is that the Eagle has the right to be fully committed to the racing line. In this case, the entire inside area ought to have been a no-go zone for the Lotus, who should have tucked in behind and followed the Eagle around. Of course, late braking barge drivers often end up in the hay bails, hopefully without taking you with them.