I don't think this is limited to medical students, but just imagine the following scenario. You just drove to campus and you're still in the parking lot/garage. A brand new Lamborghini Murciaglo stops in a parking spot. A guy gets out wearing sunglasses. He takes them off and you realize he's that guy from biochem you havent talked to yet. If I could hand out questionnaires, I'll bet 75% of people ( remember, for the sake of this scenario med students are people. You could substitute any group and I think it would still be valid. ) would immediately label him a douche bag, with half of them labeling him a super douch bag. I wouldn't go out of my way to talk to him because I doubt I could relate to him.
So, to the people who just blatantly say "car doesn't matter" I think you're kidding yourself.
I worked 20 hrs/week in a hospital and frequently walked through the doctors parking lot. It was in a medium sized city. There was always an interesting mix of cars consisting mostly of your average entry level sedans with some minivans thrown in. There were always a couple of Porsches, corvettes, or even a Lamborghini or Ferrari.
I agree that I wouldn't want a supercar no matter how much money I had. I wear my seat belt, I don't walk on the grass, and I don't speed (much) so to think I'm going to tear up my morning commute or even the backroads like I'm in the Indy 500, it's just not me. Now luxury cars otoh, can make my commute more comfortable. Give me a new Buick Regal and I'll be set. Ahhh, sensible American luxury.