An Illinois motor vehicle bill of sale documents the purchase and sale of a motor vehicle between a private seller and buyer in the State of Illinois. Prepare a bill of sale for the buyer.Include the date of sale and the price paid. An Illinois motor vehicle bill of sale legally transfers ownership of a car or other motor vehicle in the state of Illinois. Motor Vehicle Bill of Sale – Use to sell, purchase and change ownership of an automobile. The Illinois bill of sale form approves the exchange of a financial consideration for an item of property into a text register.