Plug-in hybrids combine a fuel tank and a gasoline engine with an electric motor and an onboard battery, so there are lots of different elements to consider in terms of range. We test vehicles on a 75-mph real-world highway loop, calculating a range number based on fuel tank capacity and the vehicle's fuel-economy result. What follows is a list of the plug-in hybrids we've tested with the most overall range when you combine gasoline and electric power.