* Definition of "car": Does this include trucks, motorcycles, and other vehicles?
* Data sources: Different government agencies track vehicle registrations and driver's licenses differently, leading to variations.
* Geographic variations: Car ownership varies significantly by state and region. Urban areas generally have lower car ownership per capita than rural areas.
To get a rough estimate, you'd need to find reliable data on the total number of registered vehicles (excluding things like motorcycles that may or may not be included in your definition) and divide it by the number of licensed drivers. However, even then, you'd have an approximation. You won't find an exact, universally agreed-upon number.
