A car can kill a pedestrian/bicyclist/motorcyclist at surprisingly low speeds. It's almost impossible to kill someone in a car at under 25 MPH or so (unless they drive off a cliff or something), but pedestrians can be killed by cars going as slowly as 10 MPH (they get knocked off their feet and hit their heads, usually). I read a very interesting paper by the NTSB or IIHS about that, but can't find it now.

Pedestrian and bicycle fatalities outnumber car occupant fatalities in Manhattan for this reason.

I saw a billboard last time I drove through NYC, explaining why the speed limit is 35 rather than 45. It basically said that if a car hits a pedestrian going 35, the pedestrian will probably live, but if a car hits a pedestrian going 45, the pedestrian will probably die.

You've never seen third/second avenue with a green light at 14th street. Traffic rockets through there, except during rush hour.