Credit. Union shall pay the Purchase Price to Dealer on the Purchase Date. "Contract" means a retail sales contract security agreement and disclosure statement.A vehicle payment plan agreement is a contract between a buyer and seller of a vehicle that agrees to installment payments. Eventually the dealership found another bank willing to do a 84 month loan. I'd like to take this time to review the sample contract with you to help you understand the ins and outs of a purchase contract. The final hurdle you face is signing the vehicle purchase agreement; a confusing and convoluted document that we explain in detail here.