Special taxes existed in the past, but today there are many more tax forms. The state tries to increase the revenues of the state budget through taxes in order to ensure the smooth running of the population, and it is also used as a good instrument of fiscal policy. Each individual is obliged to pay taxes to the state, while the state in turn is obliged to provide public services to the individual. The legal basis for the introduction and application of special taxes on motor vehicles is found in legislation, and the main legal framework for special taxes on motor vehicles is the Law on Special Tax on Motor Vehicles. Considering that the Republic of Croatia is a member of the European Union, the tax system of the Republic of Croatia is harmonized with the legal acquis of the European Union. The paper presents examples of tax calculations for motor vehicles using diesel and gasoline fuel as the two most common drives in the Republic of Croatia that are used. This tries to show how big a role environmental protection actually plays in special taxes on motor vehicles.