Forget about sticking your head out of the window. Get your whole body out of the car. Turn around on the spot until the wind is on your back and the noise is the same in both ears. Provided you are not wearing a hat or deaf in one ear, you are now roughly facing the same way as the wind is headed. This is how to assess direction.
Now walk forwards at a brisk pace away from the wind. Is the wind still on your back? If it is, then the wind speed is greater than your walking pace, which for most men is around 4 mph. If you can't now feel the wind on your back then you are going faster than the wind.
A 4mph broadside wind will make your 177 pellet at 12fpe drift more than two inches at 50 yards.
Hope this helps. Wind assessment is part physics and maths, and part experience, and part luck as well. The first you can learn without even touching a gun, the second you can now get a handle on with Brian's excellent program, and the third, well, you're on your own with that.