Has there ever been an attempt to put a modified sail on an automobile to enhance gas mileage?

Question

For instance, at a certain speed, a sensor would calculate wind direction and raise a lightweight sail to take advantage of the wind. Would this be efficient? Your thoughts.

Answer 1

Once your car accelerated over the wind speed, your sail would only create drag.  So to drive on the interstate you'd need a favorable wind at near hurricane strength.

Answer 2

Think salt flats or similar area without overhead power lines.These would be the only areas where a sail assisted auto would be practical and then only at low speeds.

Answer 3

corners and "tacking" would be interesting,,,,passing even pretty cool,,imagine passing and 1 of ya gonna loose the wind help..heh