The temperature at which a car engine will freeze is -32 F if using Antifreeze in engine.
If the car engine has only water then the car engine will freeze when the temperatures reaches 32 F or below.
The longer the frozen water stays in the cars engine and cooling system the faster the engine will crack and the hoses as well as the radiator may crack and burst open as well.
When living in cold climates you must use antifreeze which protects the engine from freezing at temperatures above -32 F.
Leaving water to freeze in an engine will cause the engine to crack and break and you'll have to replace the engine and that is very expensive.
At -36 degrees Fahrenheit (that's -38 degrees Celsius), antifreeze and coolant will start to solidify, making it very difficult for your engine to turn over.
One of the most serious mechanical faults that can occur during the winter, however, is a frozen engine.
If you use water rather than good quality coolant/antifreeze in your car's cooling system, it will freeze causing huge internal pressures (which is liable to cause severe engine damage).
If the antifreeze and coolant is mixed correctly (a 50/50 mix of antifreeze and water is ideal), the ethylene glycol can keep your radiator fluid from freezing even in temperatures reaching as low as 30 degrees below zero and also keep those fluids from boiling in temperatures reaching as high as 275 degrees Fahrenheit.