I believe even for a country the with the population and size of Norway 2015 is a very short transition period to accomplish a program like this. Here in America I think something like that could be phased in over a 20 year period. This would allow the power infrastructure to be put in place that would power all the electric cars that would over the course of time be replacing the gas powered ones. People will resist a plan that forces them to scrap a car that still has a useful life however most people are done with a car in five to ten years. As the older gas powered cars become worn out and are scraped over the years the power grid and generating plants would be growing in capacity. A timetable like this would allow minimum hardship and make the transition practical. A program like this is only worthwhile if the fuel used to generate the electricity is anything but oil.