Originally Posted by ScubyPhilly
650 RPM is perfectly fine for idle. Coolant temp is the temp I was looking for, measured at the hot side of the radiator IIRC. The engine may even idle a little lower if the IAT and coolant temps are a little lower. There is a heat compensation curve, too cold and idle will rise, too hot idle will raise. There is also a lower AFR in these conditions in an attempt to use the cooler fuel to lower the temp, or increased combustion to raise the temp.
Side note: 0-60 in a zippy 10.1 seconds. What is the new gen prius? 10.0? I know it's not a track car, but damn...