Conveniently, both the sensing element of the thermostat and its control valve may be placed at the same location, allowing the use of a simple self-contained non-powered thermostat as the primary device for the precise control of engine temperature. Although most vehicles now have a temperature-controlled electric cooling fan, "the unassisted air stream can provide sufficient cooling up to 95% of the time" and so such a fan is not the mechanism for primary control of the internal temperature.
Luckily, both the sensor and regulator components of the thermostat can be placed in one spot, allowing the use of a simple, non-powered thermostat as the main device for precisely controlling engine temperature. Most contemporary vehicles have a temperature-controlled electric cooling fan, but "the natural air flow is sufficient to cool the engine up to 95% of the time," making such a fan unnecessary for primary temperature control.