With fan on full blast, car moving at 60 mph, the transfer of heat from the coolant may have been high enough that 1/2" diameter on the exit matches the change in density and viscosity.
Sounds good anyway.
Right?
no?
Com'on. Some engineer probably calculated that out.
Maybe the same one the figured out small bolt pattern was that was needed for small cars.
And compacts also only needed 18 gage wires to the headlights.
...