The indicator shows the average age of registered passenger cars for the period 1992–2007 in Slovenia and for the period 1995–2006 in the group of selected European countries. The environmental and safety standards of vehicles are constantly improving; therefore, the new vehicles are on average less polluting, generate less noise, consume less fuel and better protect the users against accidents. The indicator of average age of passenger cars indirectly expresses their environmental efficiency.

An older vehicle fleet generates more emissions than a younger one, but more rapid vehicle replacement has the disadvantage of increasing the amounts of energy and materials used for vehicle construction, dismantling and recycling. The European Environment Agency is warning that the information on the average age of a vehicle fleet alone is not sufficient in order to assess its overall environmental performance. Information on the lifetime of vehicles would be helpful to complete the picture (EEA, 2007).

The average age of passenger cars in the EU decreased from 7.82 years in 1995 to 7.65 years in 2006. In some new EU Member States the age of passengers cars has been decreasing primarily on account of an increased GDP, accelerated abandonment of old passenger cars and the policy of encouraging the replacement of older vehicles with new ones. In Slovenia, the average age of passenger cars has increased since 2001 by almost a year (in 2001 6.9 years, and in 2007 7.7 years). This means that new technologies are introduced gradually and that the vehicle fleet is mostly less environmentally-friendly.

Measures introduced by countries to renew the vehicle fleet include financial incentives for their renewal or the abandonment of old and used vehicles, management systems for used motor vehicles, import bans on some types or age of vehicles and mandatory periodic roadworthiness tests.

In EU countries, some systems of incentives for the renewal of the vehicle fleet have already been introduced; however, no common policy of such type has been set yet at the EU level. Incentives may include financial compensation for the abandonment of an old vehicle without the mandatory purchase of a new one, or financial compensation for the replacement of an old vehicle with a new one or such that is less polluting to the environment. There are some administrative measures without direct financial effects, but with an indirect influence regarding the decision on the replacement of an old vehicle. In Slovenia, such incentives have not been introduced yet at the state level; however, some manufacturers have included them in their sales campaigns. These measures influence the environment in two ways: positively by reducing the environmental pressure and human health risks due to the renewal of the existing vehicle fleet with newer, technologically more advanced and cleaner vehicles; and negatively by reducing the lifetime of vehicles, increasing the amounts of energy and materials used for the construction of new vehicles and the dismantling of older ones. An environmentally important part of vehicle fleet renewal is also the management system of end-of-life vehicles, which is mandatory for all EU Member States on the basis of the Directive, adopted on 18th September 2000 (no. 2000/53/EC). Its objective is to protect the environment by preventing pollution with end-of-life vehicles as well as the promotion and support of the collection, recycling and reuse of components of vehicles. The main requirements of this Directive are:
- establishment of the collection system for end-of-life vehicles across the country;
- by the end of 2006, at least 85 % of the weight of end-of-life vehicles should be recovered, and by 2015 95 % by reusing or recovering at least 80 % (by 2015 85 %) of the material;
- after 1st July 2003, the use of cadmium, mercury, lead and hexavalent chromium is prohibited in the manufacturing of vehicles;
- manufacturers or importers shall carry an essential part of the costs for the recovery of vehicles placed on the market after 1st July 2002, while after 1st January 2007 for all vehicles notwithstanding the time of their entry onto the market;
- a certificate of dismantling/destruction of a car must contain specific data and shall be mutually recognised by the Member States;
- Member States must report to the European Union on the dismantling process.

In the European Union, approximately 75 % of all vehicles are dismantled. The objective of the Directive is to increase this share to 85 % by 2006, and to 95 % by 2015 (MESP, 2006). Slovenia settled this area in 2003 with the Decree on the manner, subject of and conditions for performing public utility service of the management of end-of-life vehicles (OG RS, no. 18/2003).

The import of used vehicles that do not comply with the established safety and environment protection level is, in Slovenia, prevented by the legislation. Used vehicles that are registered anew must comply with the requirements of the Rules on devices and equipment of the vehicles in road traffic (OG RS, no.17/2000). A significant provision of these Rules, referring to the construction characteristics of vehicles, is that all vehicles, registered anew in the Republic of Slovenia, must contain equipment for the regulation of exhaust gas emissions meeting the lowest requirements:
- of the Directive 94/12/EC for passenger and light goods vehicles;
- of the Directive 91/542/EC for buses and trucks, and;
- of the Directive 97/24/EC for two- and three-wheeled vehicles.

Regular roadworthiness tests are of major importance for the reduction of the environmental impacts of vehicles and for the timely abandonment of inappropriate vehicles. Properly maintained vehicles can be of a higher age as long as their environmental performance does not differ too much from the newest technologies (EEA, 2007). Mandatory periodic roadworthiness tests in Slovenia have been carried out for a long time, improved by measurements of exhaust gas emissions since 1st December 2003. This measure shall directly reduce GHG emissions, since cars are not allowed to exceed the approved values of these emissions. Furthermore, the measure shall also influence the maintenance of vehicles, which additionally contributes to the reduction of emissions.