The quote you've selected is an unfortunate example of the NYT poorly summarizing the findings of their own study (not your fault, they're the ones who wrote it). You can find a more precise explanation at the end of the article in the Methodology section.

"200 to 400" is from their model of decreasing hood height for existing collisions. But from the article:

> There are two reasons bigger vehicles are deadlier: They have taller hoods. And they tend to have larger blind zones.

It doesn't appear that NYT included in their model the larger blind zones and how that causes more collisions. So they shouldn't have said their 200-400 estimate covers the increase in vehicle "size" when it only models one dimension of size growth.