On Mon, 16 Jan 2006 19:27:30 +0000, The Natural Philosopher wrote
(in message ):

Lithium cells have a theoretical energy desnity of 350Wh per kg...and
already up to half that or more has been achieved.

So 3kg per kWh, or 300kg for a 100kWh battery. I think that's wiped out any
weight saving from removing the engine & gearbox from most small cars. That's
assuming development to the full potential, at present it's going to be a
600kg battery.