Quote from BeNoM : [...]

Even if they did change the collision model, you wouldn't go "flying" you would just get hit normally with invisible parts of the car or you would morph through a car a tiny bit.

[...]

Wrong.If your VOB collision is smaller than the original (which can be a significant difference btw), then your car will not slow down until your car (on their screen) is actually inside the other player's. Due to internet latency and relatively low packet rates, your car can be inside theirs a significant way before their collision detection responds.When the detection triggers, it will then push the other player's car away - how fast depends on how far your car was inside theirs. If it's more than a few inches, that can be quite fast.You can test this effect by deliberately warping cars in to each other - there are a few ways of doing that without needing mods.LFS uses some pretty good prediction to minimise or even eliminate this under normal circumstances, when collision meshes are synchronised. However, if the meshes are different across clients, it doesn't really work any more.Even if the collision is slow enough to not cause significant warping (very difficult with internet latency), it is possible to push the other car away without it appearing to even touch yours on your screen.In servers where there is close racing or other contact, that can give a clear advantage - if you can push them and they can't push you - and will ruin everyone else's enjoyment.I've been admining servers where this has been a significant problem for several years. To the untrained eye, the problems often look like lag hits, but there are other clues and ways of testing for problems.It's less of an issue these days now most collision mesh changes are caught by the new-ish OOS checks, however there are still some problems either due to certain VOBs/hacks bypassing the checks somehow, or when cars are damaged. The former was more common soon after the OOS changes, but I'm sure there are still a few around.*The way the collisions work between different players with different apparent collision meshes is quite complex and hard to explain - I've probably missed something out.