Originally Posted by
Zaphod
The density figures provided by Doug give you an idea of how much energy can be packed into a given space and explains why the battery pack used in a vehicle is so much larger than a fuel tank. Electric vehicles store much smaller amounts of energy on board, but are generally more efficient at using that stored energy. Basically, the calculations you've made above don't reflect all of the variables involved and might not be the best way to draw energy use comparisons between the two. It gets pretty complicated!