For an exact, real temperature I no longer trust the dash gauges. They are good for direction, size of T change, but they are rarely calibrated.
I use an infrared hand held sensor under the hood to verify localized real temperatures on mine and then correct the actual dash gauge reading for what I read with the IR gauge. Right now my dash is reading about 35 F too low compared to the thermostat area measurements I am getting. I am also getting a 20 F rise from the rear of my head to front.