Cars have many accessories and extra parts that are made to either make rides more comfortable, conveniant or cleaner. They are however all different in size type and use, so some are simply situational and others are useful all the time. For instance a first aid kit is only a precautionary kit that is there for emergencies, while a radio or a phone charger will be useful any time you drive the car.
Some vehicle accessories can be pretty useful for certain types of drivers, especially for those that have a long commute or live in the scorching hot Australian climate. A solar powered fan that passively cools your car while you're not using it. But this is a comfort accessory there are more car accessories electronics have a more practical purpose.
Some accessories such as flood lights, radios, battery chargers, GPS and battery meters etc...
These are not only useful accessories but could also potentially save you from damage to your car or in the worst case scenario save your life. But some specific car accessories electronics are made to monitor and avoid ending up stranded somewhere.
An example for the aforementioned monitoring accessory is a battery monitor which shows the charge of the battery which is important for those that use their vehicles regularly and could not afford to go with an empty battery. Along with the meter they could also get a box charger which charges the battery while also housing it. And for an emergency jump starter which ignites the spark plug when the battery is empty or disconnected.
And some accessories like a dash camera is there for insurance purposes, since your camera will record everything that is in front of the car while driving. Another type of camera is the parking sensor which shows you the back end of the car's hull for those difficult parking spots.
But some of these accessories come native in some vehicles. Such as a first aid kit and a hydraulic jack which are usually provided with the vehicle and are especially useful for emergencies. The first aid kit in fact is mandatory in most countries due to their usefulness in the worst case scenario emergencies such as a roadside crash or other accidents.
And choosing the right accessory or part for your car depends completely on the need. Weather you need a GPS when traveling into unfamiliar places often or a dashcam to ensure that any accident is just that an accident.