Answer:
Doctors are a mix of many different types of people from many different backgrounds and with greatly varied interests. Income levels, while usually above average, also vary greatly.
As owner of Physicians Auto Group and www.PhysiciansAutoGroup.com, I see firsthand what Doctors drive. As you may expect, it's the same thing that everybody else drives (Just newer and nicer). BMW, Mercedes and Lexus are all on the list, but a few others stand out.
The Honda odyssey is the #1 selling Minivan in the US, and not surprisingly, the most popular van with Doctors (Yes, they have families too)
Porsche cars are also high on the list, as they are Exotic cars that can be driven everyday. Porsches to many doctors are All Season cars.
Lexus RX350's are a winner across the board. They have utility and luxury, combined with superior reliability.
Doctors many times just want the newest coolest car out. The Toyota Prius was extremely popular when gas prices were at $4/Gallon, The retractable hardtop 3 series BMW sold in scores when it was released in 2007.
In closing, Doctors drive all sorts of cars, they're usually newer and very well equipped, however they range from Fords to Ferraris, and Hondas to Hummers.