I think that a lot of it comes down to marketing position and customer education/segmentation. From a purely technical standpoint, the Prius has a 3.2kWh batte

I think that a lot of it comes down to marketing position and customer education/segmentation. From a purely technical standpoint, the Prius has a 3.2kWh battery, and the Prius Prime has a 6.8kWh battery. The Prius Prime has a rated range of 44 electric miles, so presumably if you charged the Prius up to the max, it would get 20 miles or so. As an electric vehicle, this is extremely marginal. For people who keep their car in a garage with a power outlet most every night, many people would be able to dramatically reduce their gasoline usage if they started the day with 20 miles of charge. The only problem is that it's not really an EV. The range isn't good enough where it's an EV except for road trips, and I think that on the Prius the gas engine kicks in above a certain speed or if you mash the accelerator, because the electric motor doesn't produce very much power. The result is that if you were to charge it every night, you might reduce your gas consumption by say, 75% or something. Then this leads to a psychological problem, where people want to hold certain values, or not. They don't want to hold a value half way. For example, imagine that you thought that eating meat was murder. Would you then want to cut your meat consumption by 75% and feel good that you had reduced the number of murders you were routinely committing?