Bike Awareness Sensor

  How many times do we see bikers hurt or killed in accidents with cars? How many times has the reason been "I just didn't see them." from the car driver?
  We all suffer from not being aware enough at times when on the road...maybe when tired, or when bored, driving down an endless motorway.
  My idea is that there are sensors in the rear bumper of the car that check for items of bike size. It could either be done on size, or have bikes fitted with a partner sensor, so that when the signals meet, a light and warning beep sound in the car, to alert the driver that there is a biker behind them and to watch out as they will more than likely over / undertake them soon.
  If there were 2 alert lights in the dashboard of the car, maybe under the indicator lights, then the corresponding side would illuminate, so that the driver would know from which side the bike was approaching.