Prices below the equilibrium price generate excess demand because buyers are willing to purchase more trucks than sellers are willing to sell—the quantity supplied is less than the quantity demanded at that price. Some buyers who wish to purchase trucks at the current price will be unable to do so. In order to purchase trucks, some buyers will offer higher prices. As buyers bid and drive prices upward, some sellers will be willing to sell additional trucks. Therefore, the market will move toward the equilibrium price, where the quantity of trucks demanded by buyers equals the quantity supplied by sellers.