It would be if it were a motor bike. I mean, 'motor bike'.
I've done some calculating. In a solid sidewind the pressure pushing the car sideways could be, say 500 Newton.
Under a 5% slant that would make a net forward force of 25 N.
At 65 mph, almost 30 meter per second, that saves 750 Watt on power. You would see that on your per tank average.
Better still, if you build your own 200 mpg super light 3-wheeler, this trick would still yield about the same advantage, and then it really stands out.
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2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gmeter or 0.13 Mmile.
For confirmation go to people just like you.
For education go to people unlike yourself.