[lust4speed]

Manufacturers have had 50+ years to sort out their cooling systems. We might say that they were still learning when our cars were made. The temperature reading is an average of coolant from cooler and hotter internal passages in the engine. A 220° thermostat reading is an average of say 200° coolant and 240° coolant (or even a greater spread). Personally I feel much better if my average is a combination of 160° and 200° showing 180° on a gauge. Newer vehicles with aluminum heads and some with aluminum blocks do a much better job of distributing heat and the temperature spread coming up to the thermostat is much better controlled and they can bump the overall average operating temperature higher.

An example of temperature spread would be coolant that goes from the block to the head at the front inside of the engine block/head is going to be much cooler than coolant from the passage going into the head on the outside passages near the two center exhaust ports of the engine.