The distance covered by (motor)vehicles in a particular period expressed in vehicle kilometres. Vehicle kilometre is the unit of measurement for the traffic performance representing the movement of one road motor vehicle over a distance of one kilometre. 
In this publication, the term traffic performance does not include buses, special vehicles and motorcycles. The traffic performance of these types of road motor vehicles each account for approximately 1 percent of total traffic performances of all motor vehicles. Recent data for these types of vehicles are as yet not available.