The thermostat controls coolant (and, through it, engine) temperature by regulating the flow of coolant through the radiator. A bypass tube allows coolant to bypass the radiator and flow back into the water pump when its temperature is low enough that the thermostat is closed.

Cylinder number and arrangement depends on the purpose of the engine. Smaller (four and six cylinder) engines in front-wheel drive vehicles often use an inline design which orients cylinders vertically over the crankshaft and aligns them in a row. Other common orientations are a horizontal/opposed design which places cylinders flat facing each other with the crankshaft between them and a V-type design common in six and eight cylinder engines that features one cylinder head per block of cylinders oriented at a 60 to 90 degree angle to each other with the crankshaft at the bottom of the V.

Fuel injection has replaced the carburetor as the primary automobile fuel delivery system. The main difference between the fuel injector and the carburetor is that fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure while a carburetor relies on suction to draw fuel into an accelerated intake air stream.

Maintaining proper synchronization between the rotation of the camshaft and the rotation of the crankshaft is critical to ensure that the engine's valves open and close at the proper times during each cylinder's intake and exhaust strokes.

Sensors provide the data necessary for the vehicle's computer to make decisions and monitor everything from simple vehicle information like tire pressure to complexities like the chemical content of an engine's exhaust.