A Pennsylvania vehicle bill of sale is a legal document formalizing the sale and purchase of a motor vehicle between a buyer and seller. When selling a vehicle, the seller must sign and handprint their name on the proof of ownership document.A Pennsylvania bill of sale documents the transfer of ownership of a motor vehicle, boat, gun, or other valuable asset. A Pennsylvania motor vehicle bill of sale is a legally recognized document that acts as a record of the sale of a vehicle between a seller and buyer. The Pennsylvania bill of sale form acknowledges the transfer of possession of a piece of personal property for an agreedupon sum of money.