Motorcycle to car ownership: The role of road mobility, accessibility and income inequality

Recent empirical studies indicated that motorcycle ownership grows as a nation's economy develops, but decreases once incomes have passed a threshold level. The aim of this study was to assess the impacts of relative improvements in road mobility over road accessibility (MPA) and income inequality on motorcycle to passenger car ownership ratio (MPC). Particularly, we investigated how the reverse U-shaped relationship between MPC and economic expansion varied in response to changes in the MPA and income inequality. A fixed-effects panel linear regression analysis was performed on a panel of 53 countries over the period of 1963-2013. This study highlights four key findings in relation to the impact of per capita Gross Domestic Product (GDP) on MPC. Firstly, the effect of MPA on MPC differs by per capita GDP levels. Results indicated that a rise in MPA is likely to lead to increases in MPC at lower per capita GDP, specifically increases in the number of small power motorcycles, but lead to decreases in MPC once per capita GDP levels have exceeded US$3,081. However, as per capita GDP rises beyond US$44,767, an increase in MPA would lead to increases in MPC and one would expect increases in the number of high-power motorcycles. Secondly, there is a reverse U-shaped relationship between MPC and income inequality. That is, a rise in income inequality is initially accompanied by increases in MPC, but MPC decreases once per capita GDP levels have passed a specific level. Thirdly, under lower income inequality, there is a U-shaped relationship between MPC and per capita GDP, and fourthly, under higher income inequality, this relationship becomes reverse U-shaped.