One thing is for certain, with as many Toyota Prius' on the road here in California, there are a greater number of creative minds working on solutions to bettering an already pretty decent product. The shear numbers help the business case's ROI numbers as well. This aux battery option is just one, I can imagine there are several other ideas that will be unvailed within the next year... <budget battery replacement through some refurbishment program perhaps>
don't tell anyone, but some racer friends of mine have been working on one such project... spy photo, below
