Wind at my back on '98 Dodge Stratus trip?
 

We're planning for a trip soon. We'll be going from Northern California to El Paso and back. On most trips I've gotten best FE by staying around 60mph (32-35mpg) but got as high as 38mpg at 65mph with a strong tail wind. I think that must have allowed the engine to rev closer to a "sweet spot".
I will not have made any eco mods by that time, but hope to time things to be able to drive with the wind, or at least with minimal headwind, as much as possible.
Of course, prevailing winds can change, but I know from experience within California that during warm afternoons, there's a strong north wind along at least 200 miles down the Central Valley, so we'll got on Highway 5 as we start out.
Does anyone know of a return route, such as north through Nevada, that would provide better wind conditions on the return trip? Or is it useless to even try to plan with wind in mind?
Thanks,
Ray Mac.

Planning with wind in mind isn't entirely useless - it does assume that you'll know what direction the wind will be going in the future though ;)

RPM is independent of natural wind speed. If you're going 65 in a 20mph headwind, the RPM will be the same as going 65 in a 20mph tailwind. Wind just doesn't change gear ratios... But, what you're seeing is just how much of an impact wind resistance is. Going 65 with a 20mph tailwind will have the same wind resistance as going 45mph (and keep in mind that the power necessary to overcome increases wit the cube of the apparent wind speed).

Good luck with planning your trip though :)

Thanks.
I guess what I really meant to ask is if anyone knew whether I might have less wind against me by returning north through Nevada rather than the conditions I know I will have driving up the California Central Valley.
As you suggest, prevailing winds don't always prevail.
Ray Mac