Various governments around the world can impose a tax on the liquid, effectively being able to keep that huge income stream intact. When the price at the pump is 75% tax (in my glorious socialist EU country), at 1,70€/liter...
Electric cars can use 20Amp 3-phase chargers to charge the batteries (albeit slowly) without requiring any changes in the electrical systems of a house. This makes government budget centers iffy, since they cannot easily tax you (despite the fact that in many EU countries you already pay for a yearly tax in excess of 150€).
Cars with liquid-rechargeable batteries would allow them to control distribution of the liquid and keep taxing it.