P.S. The 53 kWh figure you give for the Tesla Roadster didn't look right to me. I found THIS PDF document from 2007 which gives the 53 kWh figure, but then THIS PAGE, which appears to be more current, gives a figure of 56 kWh, which is more in line with the wh/mi vs speed and range vs speed graphs that I copied from somewhere a while back. I don't remember where I got them. Probably from the Tesla Club chat board.