Intra-car communication

Three or more people journeying together in a car, will normally, and naturally wish to converse.
Unfortunately, unless you happen to be lucky enough to be in a stretch limo, the arrangement of seats makes this rather difficult. Instead of sitting around a common focal point, all conversees are facing in the same direction.
This is particularly annoying for people sitting in the back, as it is often difficult to hear what people in the front are saying (unless front seat occupants crane their neck around to address you directly - uncomfortable for the front passenger, downright dangerous for the driver). A single passenger in the back can often be found moving their head into the gap between the front seats to talk, and when there is more than one rear passenger, they will tend to give up and have their own conversation to save hassle.

I am proposing a simple microphone/loudspeaker system, similar to that used in taxi-cabs when there is a partition between front and rear. Most modern cars are already fitted with four loudspeakers for the stereo system, so to save expense these can be used. Microphones fitted at head height in all four corners of the car would be wired through to the speaker at the opposite corner (to help prevent feedback), or possibly wired to the speaker in front of/behind the speaker. Either arrangement would not only help general conversation, but automatically simulate the natural loudening of one's voice as heard by the recipient, when turning one's head towards the source of their voice.