"An ordinary person free of water and sewage and electric mains and to build with local materials something they can use as a shelter - who knows, they might need it in future, " he added.

BBC: NEWS | UK | Wales | South West Wales | Eco house owner gives up fight

But it is a particularly good idea for an electric car because mains electricity can be used if the car is still plugged in, thus conserving battery power.

ECONOMIST: Vehicle telemetry