[aerohead]

I think it would channel air into the wake,however,I also think flow would separate at the top and sides,creating a relatively horrendous wake behind the sign.At urban speeds,as already mentioned by others,its probably a wash.But if road construction near the airport is complete now,and the taxi can actually drive at highway speed,say,all the way into city center,or out to MOPAC ,I'd say it's an energy loser.If the Austin Aztecs had any respect for their neighbors,countrymen,or Earth,they wouldn't do that.Disapproving head shake.