ColoradoStateEE1982

Physics reasons that a hybrid gets better MPG than a non-hybrid be because: 1) ICE is much smaller and more efficient than a non-hybrid bigger ICE. Easy proof would be to use identical big engines in both cars. 2) Energy is recaptured into battery by generator braking , rather than losing the energy by friction and ICE braking. YoloSwaggins is right, charging the battery while driving cannot improve MPG by "laws of conservation of energy" Energy is lost permanently converting mechanical energy to battery storage and back to mechanical energy.