This paperwork contains problems of simulation, business simulation, application and division of business simulation. Simulation is an imitation of a real state, thing or process. Main task of simulation is to reduce costs and increase production performance, and help us to become familiar with system operation, increase product quality and reduce production. Business simulation are used for an easy description of economic situations and system behavior forecast, and also are used to train manager beginners. Rent-a-car companies are also involved in this paperwork. Rent-a-car companies are renting motor vehicles ranging from hours to week, and even months. There are so many rent-a-car companies in the world, and each of them operates in a similar way. The most important rent-a-car companies in the world are: Sixt, Enterprise Rent-A-Car, Avis, Hertz and Europcar. Two most important business simulation programs Arena and @RISK are also presented in this paper. There is example of rent-a-car business simulation in Arena software.