Eli5: How does a thermometer on a car work?

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I can’t think of a location within the bodywork of a car that would provide accurate data considering wind-chill when it’s moving, excessive heat from either the engine, or stationary in the sun.

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Anonymous 0 Comments

Fwiw, cars don’t use thermometers they use thermistors. A thermometer works by mercury expanding or contracting due to temperature rising or falling respectively. A thermistor works by changing resistance in a wire based on temperature. As u/albigatin said, it is usually in the front and near the bottom, both of which shield it from ambient engine heat and with the idea that moving air will keep engine air away from it. This also keeps it out of direct sunlight. The problem is exactly what he said as well, asphalt roads especially trap heat and can be 40-50 degrees F hotter than air temperatures. Even in a moving car with the thermistor a foot higher than the road, the temperature will be a few degrees higher because of this. If your car is stopped, the temperature displayed will be even more skewed.

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