In the future, whenever that may be, a consortium of automakers have envisaged "car-to-x", a system which allows communication between cars via a mini WIFI network. Not only would the cars communicate with each other, they could also communicate with traffic signs, traffic signals, bridges, tolls and even dangerous roads. BMW has now joined the party, with the primary intent of using car-to-x for vehicle safety and efficiency.
The basis of the car-to-x network is usually a WLAN network, which is run on open standards between a consortium of automakers, and has been under development for over a decade. The consortium wants to create a brand agnostic system in the end.
The system itself does present some interesting real world use examples. For instance, the system could have important use for motorcycles, which would constantly transmit their location to surrounding cars, and so would warn the driver of a car who is about to potentially sideswipe the motorcycle.
Another case scenario involves a disabled vehicle around a blind end which could warn incoming high speed traffic to slow down.
BMW also cites use for efficiency-- imaging traffic lights warning you a few seconds before they turn green so you could get ready to go. Or cars stuck in traffic warning cars down the road that their is traffic, providing them an opportunity to bypass the traffic jam.