See the working version here.
I spent about two hours writing the first version of this, and a weekend working on this release; it's still very buggy and feature poor. Nevertheless, so far it has:
This version has a good number of glaring problems.
First and foremost there needs to be an authentication system in place. Implementing Django's built libraries for this would work, however, I decided that I'd prefer to implement OAuth in the next iteration and just allow log ins via Facebook/Twitter/Google.
There are also some data cleanup issues (i.e. if you keep clicking the refresh button on certain pages things break…) I know where the problems are, and I'll be fixing this as soon as I have spare time (a few weekends from now?)
When I have time to work on this again I'll be fixing the issues above as well as adding e-mail/text message support (I have most of it written from past projects; I just need to copy it into this project). That way all members of a car/carpool will be notified when something changes (new members, questions about time/location, etc…).