They measure the skid marks, crush damage, and vehicle displacement.
That’s the big red flag to me. This is not as much of a hard science as they would have us believe.
Probably they put the weights of the cars and the distances involved into a formula and it produced that number. If they fudged or approximated the number, the lawyers would have a claim: “What else did you fudge?”
The photos in the article don’t look like a one hundred and anything mile an hour wreck. I got hit at 50 mph. I was stopped behind a stalled car. Later, I measured the displacement of the body of my car. It was crushed 29”, and it was a station wagon with a solid frame. I don’t know how far forward he pushed me, but I know they also include that in the formula.
The county police in my old area set up a Fatal Accident Response Team with the local cops. The F.A.R.T. measured skid marks. It was also a brown car. I was surprised that they left it that way for two years before someone made them change it.