I've seen one and I live in an area where they are pretty "common".

There is one part of that old Wyle E Coyote cartoon, that is pretty true.

Roadrunners are fast as fuck. Less about the top speed and more about the agility and quick sudden bursts of top speed. Not to mention, if they really feel threatened and cant outrun it. They can fly.

I dont see many fully grown examples. I see juveniles occasionally, with adults being rare.