Cars are fragile in real life. If you watch DTM which starts in a couple of hours by the way you will see that slightest contact provokes spoilers to break apart.if you set it to 100% everything seems to fragile.
In my opinion some time 100% of damage can be too low. Every (really) light touch we have is not a problem. In real, if you touch really smoothly something like the "wall of champions" in Canada you're dead. If you get touch with another car you can have heavy damage. If you go outside the curb and you drive a wheel on the grass you can do that 1 time...because doing again could mean to see the tire and the suspension to fly away.
Some mods aren't fragile enough. Used some formula one mods where I or others have copped a whack and still got their front wings on.
The new S397 are not at all fragile enough, it is not at all realistic. Compare with ISI cars
If the component damage isn't relatively modelled correctly the overall damage multiplier could be very unrealistic.
For example, you may find that at 100% damage the nosecone never breaks off in a frontal impact yet the suspension gets bent at the slightest nudge with the wall. I find many mods have their relative component damage set unrealistically.