Hi RydgeMrPinky,
You should be able to just set the impact damage in your DM and drive the sedan into it to fracture. The impact Damage should be a value you set. In my test I just use 1.0. The Impact Damage Depth should be at minimum 0.
I used the Vehicle Template as a test and these work as intended. If you’re still having issues, you need check the collision settings for the sedan in your player character BP.