I would like to see data showing the advantage in the Prius of rear discs. A series of stops, some at maximum lockup (or attempted lockup),some on downhill stretches, with otherwise identical cars. Until there is evidence that rear discs would help, I don't take such claims seriously.
I mean claims of better braking with the discs, Dan. I just don't think 99% of us would ever see it, and the other 1% is on the track. A light, front heavy car hardly uses rear bakes at all, or it would skid. Only through repeated or continuous heating would you see a performance difference; those are the conditoins I described for a test.
I don´t think that disc brakes has any major advantage over drums for any ordinary driving, but honestly, don´t you think that drum brakes is kind of "a thing of the past" and is a bit strange on "a car of the future"? I think Volvo made their last drum brakes in 1974....
No, i don´t have a Volvo any longer. I drive a Citroen and an old Mitsubishi.
There´s no law against drum brakes in Sweden, lots of cars has drum brakes and nothing wrong with that since we have lots of salt on our winter roads that makes those disc brake calipers corrode completly. But i still think that drum brakes looks like a ugly piece of technology from the past and i can imagine that discs works better with anti lock brakes and traction control and stability control which is standard in Prius here.
I know of an old regulation requiring front discs on any car with a 1500cc or larger motor, but that's not the issue here. Explains why my brother's old Euro '67 Bug had them (along with its 6-volt electrics, covered headlights; it was an odd car in the US).