It follows that a central question for policy makers is whether avoiding this growth is possible or desirable. A number of unknown but controversial factors affect this question, including whether growth rates of car use and those of car ownership are necessarily the same, and the extent to which transport activity drives economic growth, rather than being an indicator of it. On a macroeconomic scale, transport activity can be described as “excessive” if there are more vehicle kilometres travelled than are necessary to achieve and maintain an aspired-to quality of life for a given income or level.
