alt Hacker NewsI think in 2008, it wasn't clear whether cars are going to be replaced by electric and what the final efficiency will be. It could also have been more because you would need to convert electricity to fuel first.
So I think as a conservative estimate, it kinda works.
Cost would depend on battery manufacturing but the original founders of Tesla created spreadsheets of well-to-wheel efficiency based on available data in 2002 and knew that electric came out as an obvious winner and so commited to starting the company based on that.