The PCM won't go into closed loop until the coolant reaches 172F.
Anything less than that will waste fuel and keep the PCM from doing it's job.
Although the coolant during highway travel will be cooler, you will still heat up to 206F before the cooling fans come on. At that point, you will not see anything different in driveability. The coolant and engine will remain at 206F until highway speed cooling brings it down.
The cooling fans regulate the operating temperature during performance racing (1/4 mile drag racing).
The cooling fans are disabled above 44mph by the PCM. There is sufficient airflow to cool the engine above 44mph.
This is detailed in the service manual and powertrain diagnostic manual.
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