"Matt Beard" wrote in message
oups.com...
Doctor Drivel wrote:
Have you ever weighed a full fuel tank -£50s worth?. Per weight modern
state-of-the-art batteries pack a hell of a lot of energy. These
batteries
are not available in volume yet.


Lithium Polymer (one of the best candidates for this - as you yourself
have stated) has an energy density of 166Wh/kg[1]

Petrol is of the order of 12000-13000Wh/kg[2][3] depending on the
source.

I make this about 70-80 times more efficient to carry your energy in
petrol than a battery if you ignore the fact that the fuel gets used
up. Assume that the tank averages a half-empty state you are about 150
times better off.


You have to take into account the total weight of the vehicle. IC engines,
transmissions an fuel tanks are bulky and heavy with knock ons like heavier
suspension, bigger stronger bodies, etc. The new Mitsubishi, to be
launched ion Japan in about 3 to 4 years, has an electric motor in wheel hub
setup. The total weight of the car is less vs. the IC equiv, giving the
designer greater licence.