Electrical cars cheaper than gasoline or diesel cars?

A big inhibitor to modern electrical (and even hybrid) cars today are the high costs of batteries and the rather marginal reach. A recent study of IFA (in Germany) now said that by 2020 electrical cars will be more economical than their oil fuelled counterparts. They assumed decreasing costs for the batteries and increasing costs for fuel (3 Euros by 2020, instead of 1.20-1.50 or so today). This seems to be a quite realistic scenario, maybe the assumptions were even taken with too much care. The progress around battery technologies is astonishing and it's quite clear that there's only so much oil still to be found.
A key problem of course remains how the electricity is produced. It is already possible to produce your own energy on the roof of your house with solar panels. But again, it's not quite economical to do so. So we also need some real progress here if the whole chain is supposed to make sense.
Let's see and continue to observe this space!