For me, on most tracks in R3E they're terrible and if you so much as look at them when you're at any kind of speed, you crash. I have to make it a habit to try to avoid them at all costs. On some tracks they're not too bad, but on most tracks they're lethal. That's one example. I usually watch a half dozen or more races every week from a variety of different series at a variety of different tracks and for the most part all of them attack and abuse the curbs at will with little to no penalty. Rarely do I see a car go completely sideways after touching 1cm of curbing, as happens to me in R3E on a regular basis. Sure, I've seen cars spin when they used too much curb, but for every one instance of that I probably see a hundred instances of drivers abusing the curb with no consequence.