In this list, the population data is 2010 (from United Nation). And vehicles per thousand capita mainly in 2010, but some from 2008 to 2010 (from Word Bank)
the number in the list is amount of vehicles
the vehicle includes cars, vans, SUVs, freight car, buses, trucks. but scooters and motorcycles are excluded.
各國車輛數量地圖(Maps of countries by vehicles)
各國車輛數量表格(List of countries by vehicles)