I'm looking to buy a new 2012 Prius Two and when test driving the dealer told me about these three modes: EV, ECO and PWR. He briefly explained them but I'm still confused as to when I would want to use each mode specifically. I may have missed a previous thread about this topic, but if someone could explain to me when and how I would use each of these modes? Also, the B gear was also confusing to me as well. Thanks!