Or oil-fired... maybe even gas fired... power stations... but that's a bit hard to explain to a bear of very little brain.
I have tried on a few occasions to compare the ACTUAL total energy expenditure of different types of car and it is extremely difficult to do.
No matter whether you know the engine efficiency, it is the unseen energy costs that are hard to calculate...
When you start to look at how much energy it takes to drill, transport, refine, & distribute petrol/diesel and compare it with the amount of energy it takes to generate, & distribute electrical power (sharing a proportion of the construction costs of any power station etc.) you soon get very lost in unknowns. Then there's the environmental impact of disposing with all those nasty battery chemicals when the car eventually dies.
In short, despite my best efforts, I cannot really work out whether electrical cars are actually a good thing for the environment. Especially when you compare them to biodiesel running at the 100+mpg now attainable through mature diesel technology. Personally I think they might prove to be nothing more than a tax dodge; YOUR emissions end up being low but your overall environmental impact might be just the same or worse. Unless the nation makes a comprehensive switch to renewable / carbon neutral energy sources for electrical power generation then you are just passing on the emissions upstream, and leaving a legacy of toxicity to deal with in 10 or 15 years time.
Talk about a tangent! Sorry
John