Car Sharing Trends
Source: Innovative Mobility Carsharing Outlook: Carsharing Market Overview, Analysis, and Trends - Summer 2013 http://tsrc.berkeley.edu/node/629
Susan Shaheen et al. at UC Berkeley have some nice trends on Carsharing in the US in their report Innovative Mobility Carsharing Outlook: Carsharing Market Overview, Analysis, and Trends - Summer 2013. I don't know where market saturation is, but we are not there yet.