A basic first-aid kit comprises gauze dressings, crêpe rolled bandages,
safety pins, disposable gloves, etc. Keep the first aid kit updated and sterile at all times.
If you are suffering from an illness and are on a regular dose, be sure to keep one extra set of medicines and sufficient food in your car all the time.
Having a flashlight handy in a situation where you are stuck in extreme traffic or when stranded will be helpful.
Always carry a sufficient amount of cash, irrespective of being stuck in a car or not.
Being stuck in your car for hours directly means a dying cell phone battery. Carrying a charger is a good option!
Traffic police can demand your documents at any moment. So, ensure you don't travel without your documents.