Last week I installed a trailer hitch on my Infiniti G37S Coupe. While searching for bike rack options I found a post on the MyG37 forums showing how to use off-the-shelf receiver and adjustable hitch from Northern Tool to make a simple 2″ hitch.
A “store bought” hitch for the G37 or Q60 Coupe runs about $300 installed. Total cost of this mod is under $100 and took about an hour to install. I think this method could easily be used for other cars.
Full details on how to do it can be found here: DYI: 30-min Invisible Trailer Hitch Mod