Head, Tail, Crosswind Detection?
 

To all you hypermiler geniuses,

If you're so smart, design something that tells me what are the prevailing wind direction conditions; headwind, tailwind, or crosswind.

Thanks!
Doug in Oakland, CA

Doug, I use the flags atop tall flagpoles as my wind direction source. There are enough of them on my 54 mile commute to keep me updated on this very important factor. ;)

How stupid of me. As a sailor, I'm embarrassed.

But how did you afford to pay for each of those 54 flagpoles every mile along the way? ;)

Mount a small Navy flag on your fender? :)

Leaves on the trees / grass / flags / etc.

I salute your answer and defend your right to say it!

I use an app on my iPhone called "WindCompass". It tells me wind speed and direction. :)

I also try to look at the leaves on trees

My Honda Fit, with its incredible square footage of flat sides and low weight, lets me know all about the wind. :p

Do what sailplane pilots do: tape a short piece of yarn to the center of the windshield. Of course this only gives you relative wind, but it'd work well for crosswinds.