Think about electricity as marbles in a tube- you push on the marble on one end, and almost instantly the marble on the other end moves. You could put a match box on the end of the tube and you can still easily push the marble- but it is a little harder to do, but that is work performed.
It is really the same thing, Voltage represents a difference in pressure (charge to be specific)- the pressure of electrons (and protons- but they aint budging, unless your talking about inside a plasma field (like a neon sign)) You have one wire with high pressure (dangerous) and one wire with low pressure (less dangerous and depending on design totally safe) but in reality they are both the same wire- just different ends.
When a magnet passes over say a coil a copper wire- that magnetic field pushes the electrons in the same direction. In the direction it travels becomes the side which is now under higher pressure. In order to make anything under pressure takes some oomph- and that oomph is energy required which will mean more gas is needed to drive the same distance at the same speed.
Then you have to factor in efficiency- a car is 20-30% efficient, it has to be able to operate in all sorts of ways- sometimes you have to hit the gas to get on the highway, sometimes you are backing out of your driveway- and you don't want to wait 2 hours for your car to warm up. A power generation facility is designed to run one way- optimally their engines are not changing rpms- there is no need for transmissions and other energy robbing but vital components for a car which is why they are closer to 80-98% efficient at producing power from fuel.
Also the amount of infrastructure in my opinion would NEVER pay off- by the time the system is rusted and falls apart it will not have produced more energy then it took to construct. Mining ore, refining ore, machining metal takes GREAT deals of energy.