I'm a hiring manager and have been for quite a while. I've been through numerous HR sessions about what kinds of questions are legal to ask and what are not. Asking if a person owns a car is *not* a legal question. You may ask if they have a reliable way to get to work, but that's as far as you can go.

If you ask if they have a car, or what kind of car they have, you're in discrimination territory. You, as a hiring manager, could make inferences about the individual that may or may not be valid based on the method and type of transportation they choose. For example, if they have a beater VW bug, you could infer that they're poor while if they have a brand new Caddy you could infer that they're not. Income levels are not to be considered in evaluating a candidate for a job.

The only exception to this rule is a job where the vehicle will be used as a part of their required and documented job duties, such as an outside sales employee, where the company does not provide the transportation. However, for most inside positions (clerks, programmers, bean counters, etc.), this would be an illegal requirement.