@Matthew Olszak hit the nail on the head. Many investors don't care about fancy cars, but who is your target audience for selling homes? The average American drives the nicest card they can afford to make payments on. People in general believe cars are a status symbol. So the question is do you want to meet people driving $40-60K vehicles in a 15 year old Chevy worth $3K on a good day? I certainly don't think people will respect you more for driving a sh1tty car. Maybe they won't care either way, but some may judge you or your success by what you drive. That is just how some people measure success. I know it sounds dumb, but I can tell you living in a neighborhood where everyone is getting new cars every two years, that is just how it is.
I generally advise people to drive a less expensive used car, but my exception is real estate agents. I would either lease something like @Russell Brazil suggested, buy a less expensive new car or buy a luxury used car. Either way it is a tax write off. You can find used Caddilac or used Lexus with nice leather interiors that don't cost very much. It will help put off the image of successful real estate agent, versus new and broke. As others mentioned your car should always be clean inside and out. A clean used car looks better than a dirty new car.
I do have to call out my good friend @Jay Hinrichs who says cars don't matter, yet owns his and hers Tesla models. I am pretty sure if Jay picked up a banker friend in a 15 year old chevy that it would raise a few questions. I love Tesla, but it is hard to claim that buying one is the "economical" decision. Even after $7500 rebate, when it starts out at $70K to $140K, arguably the tax credit doesn't do much. That being said, if you have the money, live in luxury! I am just jealous Jay...
For my rental business I drive a used minivan. Tenants don't need to see me roll up in anything great and it is practical for when I need to do work. It easily converts to a child hauler and road trip mobile. The best feature is I am stealth to police speed traps. Ever see a light blue minivan pulled over?