It's not a petrol-equivalent figure, like the EPA's MPGe figures. It is purely how much petrol it uses on the test cycle, which is a 'fix. For PHEVs the nedc cycle is basically meaningless as it is totally dependent on your particular usage pattern - that is to say it is even MORE meaningless than other NEDC figures!i've seen 400+ mpg quoted for the i3. Best my Rex can do, £ for £, is 120mpg. The unit price of electricity in N Ire is 18p inc vat; ~50% more expensive than E&W; but even allowing for that, where do BMW get the 400+ figure from...a solar panel user?