Hey! This is a really great idea. We could just pick some starting point, could be a unique tree or a road marker, and then use a simple stop watch while you drive to another marker. If you encounter traffic, that's fine, just specify so, such as... "Bill: Sample Rd, 12:21 mins (got stuck behind a Grandma for 2:33)"
Or, better yet, if you have a GPS enabled smart phone, you can use the free Endomondo phone app to show our average & top speeds and everything.
Hmmmmmmmmmmmmmmmmmmmmmmm This makes me want to get back out on the mountain roads!!