A very interesting topic for thought experiments. I suppose almost everyone
who has even a moderate interest in vehicle aerodynamics harbors a secret
desire to build a backyard wind tunnel.
Of all the possible configurations, my musings have settled on an open air
arrangement. Perhaps it's overly simplistic, but I have been thinking:
* Get a piece of level land in an area that is frequently very windy
(*See refs below.)
* Ensure that there is a clear path upwind; no trees, buildings. etc.
* Install a ground-level turntable (~ 20 ft diameter?) to point car upwind.
* Have rollers so powered wheels can drive un-powered wheels to wind
speed.
* Do smoke/tuft tests to your hearts content including wind off-center line.
It seems like all the height, width, and length issues would not apply.
With luck, if you built it ,""they would come."
Of course some accomodtions would have to be made for non-windy days/nights.
* Windy US places refs:
Wind Energy Resource Atlas of the United States, Map
Wind Energy Resource Atlas of the United States, Text Descriptions
Top 10 US Cities Weather Facts and Extremes