I have had to listen to HR lawyers from multiple companies come and speak to hiring managers about what is allowed and what is not allowed. Perhaps what you say is true in that it is not explicitly disallowed, but asking about a car is dangerous since it can be associated to protected classes. There are religions associated with car ownership or lack thereof, and often poverty and racial class are associated. Ask about a car when not required, and if one of the other elements is present and you get sued, kiss your wallet goodbye. Perhaps it is a difference between coroprate HR policy and law, but more likely than not, the question is "can you reliably get to work on time." that is all they need to know. Since the OP already has the job, I still suggest saying nothing about mode of transportation and just start riding unless her job description requires a car. Unless she is late, there is nothing to talk about.