Had a very rainy autocross last Sunday. Tried to mount the HERO on the outside but between all the polish and water on my car there was no way. Windshiled is Rain-x'd so no luck there, either. It was a constant deluge.
Attached it to the inside windshield next to the mirror mount, so it rattled a little but it stayed put. I ended up doing OK overall, but I was on the slower end of the field.
It was so wet, you can see drips of weater on the INSIDE of the windshield from condensation. Should have used Rain-x anti-fog.
Love this camera.
http://www.youtube.com/watch?v=Uv-HuL434gk
