Once the engine is running, the alternator provides electrical current to recharge the battery and power the electrical system. The alternator is driven by the engine's crankshaft and produces alternating current (AC) which is then fed through a rectifier bridge to convert it to the direct current (DC) required by the electrical system. A voltage regulator controls the output of the alternator to maintain a consistent voltage (approx. 14.5 volts) in the electrical system regardless of load.

Modern car engines are cooled by liquid which circulates through the engine block and cylinder heads absorbing excess heat. This liquid is made up of half water and half antifreeze (commonly, ethylene glycol) which both keeps the water from freezing at low temperatures and raises its boiling point making heat transfer more efficient.

The lighting system consists of interior lights, instrument panel lighting, headlights, and taillights. Like household electrical circuits, the vehicle's lighting system is protected from current spikes by fuses and circuit breakers.

Spark plugs receive current from the distributor and use it to spark combustion in the combustion chamber of a cylinder.

The transfer case splits engine power between the front and rear axles of four-wheel drive vehicles.