I find that most motorists suck at estimating the speed of cyclists. The SUV probably thought they had gotten far enough ahead and probably don't encounter too many cyclists exceeding 20 mph.
I routinely get passed doing 25-28 mph on some of the busier stretches of my commute just so people can slam on their brakes at the next stop sign. I really don't think (in general) that they thought I was moving that fast and they just assume they need to pass me.
And no, I can't maintain that pace the whole time. A more normal cruising speed for me is 19 mph.
EDIT: This is in a 25 mph zone
Last edited by bengreen79; 07-11-13 at 05:57 AM.