If you hit a wall hard enough, or hit another car hard enough, it simulates the damage.
So you can pit and have it fixed.
For example, if the motor blows up, it'll be an hour + long required repaired time.
Or if you hit it hard enough, the sim says "you're done"
In these sprint races (under 2hrs) you usually are pretty much done if you get any sort of damage.
No cautions in our races so no way in hell to ever catch up.