The definition of a car fleet includes a set of all transport vehicles of an particular autotransport company (cargo vehicles, tugs, trailers, semi-trailers, solo buses, articulated buses, etc.). With the constant technology advances, the demands of logistics companies have become ever greater, and logistic operators have to carefully select the fleet because selection mistakes can reflect in bad business. When choosing a car fleet, they have to consider all the elements that affect the reliability of the fleet. One of the elements is the maintenance of the fleet. It consists of a series of measures and activities that need to be implemented in order to maintain, optimize the availability and utilization of resources in order to meet the tasks and objectives of successfully running a car fleet. The main maintenance costs of the car fleet include preventive maintenance costs (regular annual or monthly service, replacement of defective parts and repairs), fuel consumption costs, legally required registration and vehicle technical inspection. Financial items (vehicle purchase through leasing or credit) are also added to them. The subject of this paper is to clarify the meaning of the car fleet and to make an analysis of the maintenance costs of the fleet. Main paper cost analysis was concluded by analyzing maintenance costs of the car fleet owned by company Zagrebgradnja d.o.o which has a heterogeneous car fleet. Cost analysis has concluded that the company could further reduce costs by introducing a professional satellite vehicle tracking and fleet management system (eg Smartivo) and more regular vehicle examinations.