This document discusses plug-in electric vehicles (PEVs) and grid-enabled vehicles (GEVs), which can be charged from the electric grid and allow bidirectional power flow to discharge energy back to the grid. There are three types of GEVs: hybrid or fuel cell vehicles, battery-powered or plug-in hybrid vehicles, and solar vehicles. GEVs have lower operating costs and reduce emissions and oil dependence, but disadvantages include high battery costs, limited charging infrastructure, potential grid overloading, and fire risks.