This link is apparantly a poster session, mostly graphics. The fun part is on pp. 17-20, wherein he suggests one might benefit from different wheel coverings front and rear.
http://www.cfd.hu/pdf/10%20Dr.Regert...2010.11.11.pdf
Anyhow, this stuck me as prime Ecomodder material, deserving of it's own thread. Also, here's a more detailed paper with some cool CFD pix of vortices around wheels.
http://www.ara.bme.hu/~regert/public...s_cmff2003.pdf