The car ownership puzzle: Deconstructing the role of parking, sprawl, and mobility

While many studies have explored the relationship between the built environment and car ownership, few have simultaneously considered the contribution of parking. This omission raises concerns about omitted variable bias, resulting in potentially misleading planning strategies. This study jointly examined the influences of the built environment, parking, and mobility options on commuters’ probability of owning cars, applying gradient boosting decision trees to data collected from Xi’an in 2019. The results showed that although parking supply and costs are important to car ownership, their predictive contribution becomes negligible once other built environment variables are controlled. Crucially, omitting parking variables does not significantly change the influence of important built environment variables. Beyond parking, distance from home and the workplace to the city center, bus stop density, and E-bike ownership are key predictors of car ownership. These findings suggest a policy hierarchy: directing growth inward acts as the foundation, alternative transportation options serve as “carrots”, and parking policies function as “sticks”