C.M. may not have had the pleasure of driving in the District, but I have. It is truly insane... but then so is L.A., Chicago, Atlanta, etc. Your comment takes the topic off on the "overly-aggressive driving" tangent. I see people deliberately accelerate to block out cars that are trying to merge in front of them - happens all the time. Give me SUVs over those a-hole drivers any day of the week.
What you're really seeing most of the time is people in the left lane closing up to prevent some idiot from trying to gain one or two car lengths by passing on the right; I rarely see anybody trying to cut anybody off from a legit merge situation. That sort of thing is normal D.C. driving.
GIVEN that the traffic is that close much of the day, I would REALLY like to be able to see ten or fifteen cars down the road, rather than just the back of the van or SUV one or two cars in front of me, i.e. have some inkling that I was going to need to use brakes before the brake lights in the van or SUV one or two cars ahead came on but, lo, I can never do that anymore because one in every three or four cars in the mix is a van or SUV, almost invariably with just the one sorry turkey in it. Like I say, don't ask me to sympathize. A $15,000/yr tax for using such a vehicle that way would be about right.