battery packs cadillac escalade carbon dioxide emissions combustibles commercial transportation industry compressed natural gas conventional gasoline conversions efficiency capabilities electrical motors electricity electric vehicle emissions energy storage systems ford escape fuel prices garages gas prices gas tank green cars hybrid electric vehicle hybrid electric vehicles hybrids hybrid vehicle hybrid vehicles hydrogen internal combustion engines launch lead acid batteries lexus suv liquid natural gas massive improvement nickel metal hydride potential power power sources price of oil prius public transportation ress solar power teen children toil toyota prius vehicle options wind power