Using oil for powering cars/plants is a giant fucking waste.
1) It is far less efficient than other sources of power.
2) It produces wastes.
3) It can be used for far better purposes.
If you think that oil is essential for the survival of humanity, you are very wrong. It is pushed down our throats by greedy corporations. Also there are far more reserve than you believe.
FYI when big car manufactoring companies started out they tested different kinds of engines. The electrical performed better than the internal combustion engine at every single category. They stilled used the ICE and through the years more researched was done and that is the reason ICEs are more advanced now.
That is beginning to shift now. Solar, wind and tidal energy is where it's at. Pure, renewable energy. See the new i series from BMW. They are gonna be released in 2013.
Future is closer than you think.
Flying cars though won't happen soon, I think. I can see it more like in "I, Robot".