The swapping out of batteries is a good idea.

Lets say batteries are good for 2000 charges and cost £6000.

Then each petrol station could sell the charged battery (On loan) to the car owner for lets say £20 a time.

The station holds a bank of batteries. When someone comes in with low power, they hand over theirs and get a fully charged one as a replacement.

Punter gets 300 miles for £20.

The station makes £40,000 turnover from each battery life cycle.

Problem is, the batteries are harmful to the environment to make. And on such a mass scale, they could even be worse than fossil fuels (Which will still be used to charge the batteries anyway).

Hydrogen fuel cell time.

Paris, because she would buy one.