Supplemental Material for: Exploring the joint evolution of motorcycle and car registration in a developing megacity

This record contains the Supplemental Material for the manuscript "Exploring the joint evolution of motorcycle and car registration in a developing megacity", submitted to the Journal of Urban Planning and Development (ASCE). The study uses ARIMAX and VAR/VARX time-series models to examine how economic growth, fiscal policy changes, ride-sharing services and the COVID-19 pandemic influenced motorcycle and passenger car registrations in Dhaka and Bangladesh from 1999 to 2024. The supplement includes: Table S1: detailed stationarity test results (ADF, PP and KPSS) for each series. Table S2: full ARIMAX model fit statistics and residual diagnostics. Figs. S1–S4: ARIMAX residual diagnostic plots. Figs. S5–S8: stability test results (OLS-CUSUM) for the remaining VAR and VARX models.