I changed pressure_sidepods from 500 to 2000 and did observe change in the coolant temperature. The trend looks reasonable, so I am thinking this mismatch between simulation result and test (coolant at 80degC) is most likely (1) parametrization and (2) the way some components are represented.
I observe in Simscape Result Explorer that each heat exchanger is rejecting >10kW of heat, these are reasonable numbers. Of course, it also depends on how big your car is. Do you know how much heat they should reject? In the test data, you should be able to find out from inlet & outlet temperature, flow rate and specific heat.
Another thing to think about: the engine thermal load is now modeled as a temperature boundary at the pipe wall at 383.15K. As the coolant temperature drops at the heat exchangers, the temperature difference in the engine "pipe" increases and more heat will enter the coolant stream, hence more heat needs to be rejected. Is this the most reasonable way to represent the engine? Will a heat flow source be more appropriate? I'm not sure. Just wondering.
One more comment: I saw you are using an offset to convert K to degC. You can use the affine conversion in the PS-Simulink converter to do the same thing, without extra blocks. Details here: https://www.mathworks.com/help/simscape/ug/how-to-apply-affine-conversion.html
