How about some Bat Wings Batman!
 

I am hoping this is the place to put out those really far out ideas that may by some freak of nature turn into a reality. What about a car having some retractable panels that could open up (expand, slide out, etc) that would assist in catching a tail wind and adding FE. We all know about traveling cross country and getting some great mileage by being pushed along by the wind.... Or would there be such additional drag that would offset most mpg gained? Instrumentation could tell you when to open up the Batwings or do it electronically.... Have I gone off the deep end... :eek:

Is that what I'm saying? Not sure. How about a pushing effect like paddling a canoe across the lake and you raise a sail and all of a sudden you are really moving out. I guess maybe I don't know for a fact that if you driving a car at 70 mph and you have a 30 mph tailwind will you get better mpg..... Seems like you do... or would.... or could.

While you could get a benefit from trimmed airfoils (sails) in crosswinds, you will only get an additional benefit to an additional surface area when you are going the same speed or slower than the wind when it's from behind.

What you find with a tailwind is that it is reducing losses, you can go and create a whole bunch more losses for it to reduce if you like, but it won't save you gas.

I recommend bingo wings instead.
https://www.lindabriggs.co.uk/procedures/before.jpg

LOL!

I'd rather see a vehicle body that 'slips' like an airplane in a crosswind. I doubt most drivers could deal with that though. Something like a fire ladder truck with front and rear steering. Or maybe just let the rear work like a taildragger airplane and freewheel into the wind. ;)

Front and rear (4 wheel) steering isn't completely alien. Some Mazdas had it, I think in the late 1980s. GM full size trucks have had it available as an option since 1999 or so. I don't understand how that might help FE though.

speaking of fins; i wonder if the cars of the 50's (57 chevys, caddys, almost every other kind) tail fins helped anything...

Rear steering wheels would allow crabbing into the wind, reducing both turbulence and frontal area.

From what I've read, '60s cars began to need much less HP to cruise at 100 than the fin-zilla 50s ones... to the tune of 40HP quoted for the 60 Ford vs the 59 Ford.

You do because you are effectively hitting the air at 40mph instead of 70, not because the wind is pushing you from behind!

Conversely, if you have a 30mph headwind and you are driving 70mph into it, you are effectively hitting that wall of air at 100mph.