It's sexual harrassment and it's WRONG!
Why do guys in cars think it's OK to whistle at me when I'm out for a run?
Oh I know!
It's because they can get away with it!
If a guy whistled at me at work or made some suggestive comment, I'd report him to any authority that was available to me.
And if anyone passed me on the street and did the same thing, he should prepare to take a dirt nap..or at least say goodbye to the family jewels.