It also helps if you have cash in hand or have a readily available bank draft for the total amount while adopting a take it or leave it attitude with the dealer. Nothing personal, just business.
Car salesmen routinely face people who are kicking tires while pretending to be serious buyers, people whose credit is in the tank after much discussion, or “will be back later”’; only to never return.
With car dealers it’s all about cash flow and the here and now.