Nonlinear and interaction effects of land use and motorcycles/E-bikes on car ownership

•Household wealth plays a crucial role in car ownership decision in developing cities.•Banning motorcycles/E-bikes motivates people to become car owners.•It amplifies the adverse effects of income and built environment variables on car ownership.•The associations between built environment variables and car ownership are limited in size.•Nonlinear associations between built environment variables and car ownership are prevalent. Although many studies examine the relationship between the built environment and car ownership in large cities, few focus on smaller cities in developing countries. Their nonlinear and interaction relationships are often neglected. Using the 2019 data from Zhongshan, a medium-sized city in China, we employed gradient boosting decision trees to estimate the nonlinear and interaction effects of the built environment and motorcycles/E-bikes on car ownership. We found that wealth plays a crucial role in households’ car ownership decisions. Most built environment variables have threshold associations with car ownership, but the size of the associations is limited. The findings suggest that polycentricity and densification around centers help mitigate the growth of cars. More importantly, motorcycles and E-bikes, particularly owning a second one, attenuate the positive effects of income and/or distance to city center on car ownership. This challenges the policies of banning motorcycles and E-bikes.