So, if you always want to be prepared for any eventuality on the road, here are 20 things people say you should never leave home without. I always keep a $20 bill hidden in my car in case I need to buy food, water, gas, pay a toll, etc. An emergency kit. This is a kit I put together in every single car I ever had. A firefighter friend has pulled a number of dead bodies out of car accidents where the accident only killed the car – the people froze to death.