I can tell you from experience.

The other guy gets out and tries to claim it was the car mats fault. Meanwhile I have to try and work out which dent if any in his old banger is the new one. Meanwhile his BMW needs a new front grill which will probably cost more than my car's worth.

Everyone agrees not to involve the insurance companies, me because I'm about 95% confident he hasn't actually damaged my car in any way, and him because it was 100% his fault.

And yeah I did get whiplash from that crash, but I didn't sue anyone because it went away after about 4 days.