@duo_sabre_07 Force of contact is difficult to determine, the same as position of contact. Lag and forward prediction make the game play out differently on the 2 clients involved. Hence the often weird ping pong physics in collisions. What you see is the result of your forward predicted car colliding with their real time car, while they see the result of their forward predicted car colliding with your real time car. The hit can be on your rear penal on your console, yet on the front panel on theirs. Just a little bit of lag can mean your car brakes a couple meters later on their console, carries more speed and makes an exaggerated hit which to you looks like that car suddenly takes off like a rocket for a tiny touch. Nudges are also often the effect of lag. You shouldn't drive too close since even a tiny lag spike can have big results.
To accurately determine what would have really happened you will need the server to play it out with both of your cars synchronized on absolute time. Then it can determine where a hit would have taken place and what the force would have been.
However that raises the question of responsibility. Are you responsible for what happens on your console, also responsible for what happens on their console, and responsible for what happens when things are synchronized in time. I've had penalties where I never made contact with the other car, yet they had 3 yellow bars and since my steering/brake input arrived late on their console my car on their console punted them off while I completely missed them on my console. (GR.1 woes at Sarthe) I have a couple of those gifs where I'm already alongside the other car when it suddenly takes off and disappears into a barrier. The other console would tell on me and I got a penalty for something out of my control (lag)
Hence it is better to look at things that you have more control over like did you enter the corner too fast, did you leave room, did you have a reason to suddenly brake, did you come from off road, did you steer into the other car etc. This is where fuzzy logic comes in, one or both of the consoles involved record a collision. They need to exchange that information and come to an understanding why it happened, who is more to blame. Who wasn't leaving room, who came in too fast, who is sliding out of control, who is most off the direction of travel. When in doubt, ie the scales don't tip enough to one side, shared blame.
Penalty time could also be based on the time lost by the victim (if the system can tell with certainty who the victim is, otherwise shared blame). For example a clear cut dive bomb, car enters a corner too fast, not being able to make it without going wide or sliding wildly etc. A collision occurs with a car that was within the speed range and following a normal line in the corner. Check the time difference between the aggressor and the victim when both are back up to speed, there's your penalty time. If the aggressor gives the position back, no penalty time (still SR Down), however if the aggressor goes off road after collision, give them a bigger penalty anyway for dangerous driving.
While it knows how to get around the track, it doesn't know it accurately enough. Forza has a very accurate dynamic driving line, where the colour changes to red when you should brake, but while it's very accurate, it's not 100%, sometimes you learn it's best to brake a touch earlier or later than it shows. So it would need to allow enough variation in braking point to allow for those small errors, but the problem is you only need to deviate from the ideal braking point by that small amount to take out the car in front or behind. Yes, it could catch major deviations, but not someone braking a teeny bit late to push the car ahead wide, or a teeny bit early to force the car behind to bin it off the track to avoid contact. The visible indicator of where GTS thinks we should brake is the double cones, and they're often further away from the ideal braking point than the Forza driving line colour changes are. And all that is before we allow for things like different tyre compounds, different amounts of wear, different cars, different brake bias settings, and people legitimately braking earlier but more gently to save their tyres.
Thus SR Down for both when contact happens and neither grossly miss their braking points. That would be an improvement over letting the car behind getting away with it and giving the car in front a penalty. It doesn't have to be perfect, it just needs to stop being wrong more often than right, while deducting SR for contact when there is doubt.