As a long distance cyclist, I never tended to give the wind much thought once strapped back into the rolling cocoon. On a motorcycle I rarely thought about it except on 2 lanes roads with crosswinds coming from the left so that truck wakes would never surprise or a time in South Dakota were able to converse quite well at over 70 mph (and that huge tailwind was attached to a major storm).
Today I was coming back to Toronto from the east and I couldn't crack an average of 10 LHK (23½ measly MPG) where I'd usually be 8.5 to 9 and most of you would be under 5. I was averaging 90 KPH / 56 MPH, keeping LOD moderated over all the rises, but my mileage was 10.1 LHK and it was also pretty cold - the IAT was -4C/24.8°F, coldest I've been out with a ScanGauge. Anyway, I was starting to wonder just how much the denser air affects my un-aero blob but looking at the weather logs in that area, there was a WNW wind of 22-32 KPH / 15-20 MPH so there was the missing 3 or 4 extra easy highway miles per gallon I was expecting.
A load type gauge should really be standard in every vehicle. On my bicycle it's pretty obvious, in a car it isn't, but with it, you really become aware of which roads aren't as flat as they appear, the impact of accessories, and even the wind, although it'd be nice to have a pitot tube like on a plane - so that it doesn't make you start to wonder at what temperature the air gets so thick that mileage plummets!
I want a NAV to help assess grade info but none of the main ones like the TomTom seem to have any altitude or grade info.
Excuse the ramble...