Which device is used to measure water temperature in a vehicle?

A temperature gauge is specifically designed to measure the temperature of the engine coolant or water in a vehicle's cooling system. This gauge provides critical information to the driver about the engine's operating temperature, which is vital for ensuring the engine runs efficiently and does not overheat. Monitoring this temperature is essential for maintaining optimal engine performance and longevity.

While water pressure gauges and coolant gauges may relate to the vehicle's cooling system, they serve different purposes. Water pressure gauges measure the pressure of the water in the system, which is important for understanding the pressure dynamics but does not indicate the actual temperature. A coolant gauge, although similar, typically refers to the temperature of the coolant rather than the water itself. Lastly, a fluid level indicator measures the quantity of fluid in a reservoir but does not provide any temperature information. Thus, the temperature gauge is the most appropriate device for measuring water temperature in a vehicle.