That's a fair point, in which case I would argue that the house-showing-car is a business expense, and if I had my own real estate agency, would keep the car at work, live close to work, bike to work, and take the car out to showings. Possibly even brag like "yes, I have a car, here it is, but I choose to bike."

A lower-level agent that is beholden to superiors would probably have a tough time trying to convince his agency to buy him a fancy car though.