The article deals with a method which provides unbiased evaluation of vehicle reliability. This method was developed for the needs of the Army of the Czech Republic, as means of facilitating decision making in the acquisitions process. The method uses two criteria for evaluation of vehicle reliability. The first criterion has a technical character, and the second has an economic character. In the fist case, the subject of evaluation is the vehicle availability, which describes the vehicle ability to be in a state to perform its required functions at a given point in time. In the second case, the method evaluates maintenance costs which are closely associated with the reliability level of vehicle and which usually represent a significant part of the total ownership cost of each vehicle. The authors of the method have created a model which expresses relations between the above-mentioned criteria and indicators of vehicle reliability. These relations are described by mathematical equations that allow the comparison of the reliability performance of different vehicles and can serve as a useful tool in the process of decision making.