Even before the rear MPG display, I played with using video cameras as a way to potentially replace the drag inducing rear view mirrors. I had acquired some LCD video displays and color cameras at the MIT electronics flea market. The cameras had a rather narrow field of view, so I set up four of them looking out the lower rear hatch window. I built a joystick operated 4 camera switch so I could easily select the camera. The display worked well except for when the sun shined directly on it, so I had a removable sun shield. The cameras worked very well during the day, or under street lights, but even with the automatic appture control, did not have the low light sensitivity to see much more than headlights of approaching cars. Of course to totally replace the rear view side mirrors, I would have needed two more cameras. With the correct choice of cameras,field of view, and a bright monitor, two side cameras should easily replace the side mirrors.
Several years later,at Hybridfest, I saw Bill Kinneys Insight that was set up with exactly that system, which seemed to work very well.