I use DCA on a fairly regular basis and, in fact, have had the opposite problem to you: I detest SUVs (it must be a European thing)!!! I booked my usual full-size a couple of weeks back only to show a Ford SUV in my stall! I went back to the Gold desk and asked for an exchange (secretly hoping I would get a nice Volvo, but to no avail). They gave me a Camry instead. But I haven't noticed as many SUVs at DCA as at other facilities (SFO, LAX, DFW, which, yes, are bigger airports). Sorry, that's not a conclusive answer, but the best I can do at the moment.