For most people they just do it to do it. It looks stupid on most cars. Then there are the people that have a fully built car that do it. It causes less wind resistance coming from up under the car...
oh ok, well that redeems itself slightly, i know a couple of type R Hatches in Stockbridge that have em.

those jokers are fast! hm, you guys on IA? white type R and Green type R.

pm me if so.