Doesn't have to be science involved. Common sense tells me that the newer vehicles have smaller radiators in comparison to the older ones who ran low cap pressure.
My old 58 Chevy seems to do okay without the thermostat, but if I take it out of my Caravan, it runs hot after a few miles. (very small radiator, and coolant moving very fast simply hasn't got enough time to cool) Read this on a tech sheet at work one time too, though don't remember the exact words.
