Social Car
After connected car, what I want next is a Social car.
Well, a lot of times, I wish to communicate with the driver ahead of me - mostly to abuse people who do not let me overtake (the idiots) / people who overtake me (the maniacs). However, there could also be several other cases for communication that people would come up with - (Blind) Dating while commute, Playing multi-player racing games while stuck on traffic (see the irony?), decide to car pool, conduct job search / interviews (see a car with parking sticker of a company you want to work for - contact him immediately) and so on.
So, along with the Connected Car, I propose a ‘Car Social Network’ where people from one car communicate with people in another car by contacting their IDs - which is just their registration numbers. You could add “Location” to it to enable people know someone is really around (& not attempt mischief).
There would of course be concerns about people (read: men) troubling other people (read: women), advertisers / retailers keeping cars parked at busy interceptions & spamming all cars that pass by etc but then, there can be ways to block all these.
And finally, to people who say drivers would get distracted because of this - I believe when a radio / music player was put into a car, the same concern was expressed then too.