The car industry in the Czech Republic is one of the most important manufacturing industries. It employes a vast number of people and it also creates a relatively significant part of the Czech gross domestic product and the Czech export. Regarding its importance in the Czech economy, this article tries to identify and explain factors determining the number of cars in the economy. In order to achieve it, a regression function is modeled using several variables. The basic variables as income, car prices, substitutes as public transportation, complements as fuel or roads are incorporated in the function as well as other determinants.