Wow, I had no idea that driving into a severe wind would have such an impact on MPG.

My wife took the HCH down to southern CA into a 25-30mph (or more) headwind, completely exposed (in a valley with no trees), with no other traffic. MPG went from a normal of about 48MPG down to 38MPG! Going 65mph, even.

Further down towards LA, driving along the coast, with the wind at 10-15mph headwind, she got 47MPG.

Maybe I should have realized the effect of the wind -- I once drove our Mercury Villager minivan from Phoenix to LA into a huge headwind, and I could almost see the fuel needle moving from Full down to Empty. I got about 1/2 to 2/3 normal mileage on that trip.