There are many types of technology to convert one form of energy to another. One of the main issues with moving vehicles is safe and efficient storage of the reserve energy.

Electrical motors are becoming more efficient at converting stored electrical energy into mechanical energy. So are fuel engines. Both are limited and will never be highly efficient.

If you take into account the source of the electricity used to place the energy into storage, electrical energy is not highly efficient when the whole picture is taken into account, unless it comes from wind, solar, or hydro power. Here in Michigan, most is derived from natural gas or coal, which are not efficient ways to produce electricity. Solar, wind and hydro are not capable of generating electricity within a moving vehicle, so better technology to create inexpensive electricity is needed before electric cars can be considered a solution rather than part of the problem.

Hybrid seems to be a reasonable compromise with today's technology.

Water fed fuel cells are indeed very clean. They are still not at a developmental stage where they can be applied to cars.

I have a packet from a manufacturer of zinc pellet storage systems that convert zinc to zinc oxide while releasing stored energy, and electricity is used when available to reverse the process. Cool stuff.