Well this is an interesting issue I've noticed recently.

Only at high speeds (70mph or higher), I will hear what sounds like a creaking board only for a split second. The first day I noticed this it was doing it randomly every minute or two. Every drive after that, it either didn't do it at all, or it was only once in the whole 40 mile trip.

When the noise occurs, nothing out of the ordinary seems to happen. Steering doesn't feel any different, etc. And it is ONLY at high speeds; nothing happens at all under 70mph.

Any ideas? I thought strut mounts made a creaking noise when they were going bad, but it doesn't make sense that they'd only make noise on bump-free high speed roads. The only thing I've changed recently were my wheels, and they are all perfectly balanced and mounted.

 

check under your car maybe one of those plastic covers is coming loose, either pull it off if it bothers you or re-staple it.