To find out how much it will cost to have your vehicle, all you need is a rental expense spreadsheet. Most states require that you have a Rental Expense Inventory and Report for all vehicles and it is essential in maintaining the car insurance policies. It is time-consuming but very rewarding if done correctly. A comprehensive rental expense spreadsheet with all the information about the vehicle, such as mileage, condition, etc, will help in avoiding unnecessary repairs and costly repairs.