The demand side is where it gets tricky. If there are only a few gas stations in your state it doesn't matter that the list price if oil is cheap. Gas stations will tear out their pumps as demand drops.

>They'll probably increase as gas motor cars are phased out before the process ever sink too low.

Why?

Increased gas taxes would drive behavior change towards electrics. Similar to tobacco and alcohol taxes to discourage their use.

I don't see diesel going away so soon though because of industrial, agriculture, and military use. It will probably be taxed differently according to it's use. In fact it already is taxed differently in the US for home heating, vehicle, and aviation use.

Because cars still have externalities, electrified or not. One just hopes that also increased thee gas tax too so as not to subsidize the ICE cars.

If it's about externalities then there is a ceiling on the taxes. Because combination isn't infinitely bad.

If it's about revenue, taxing combustion engines gets less attractive the smaller the market becomes especially if it's easy to switch.

And if it’s about revenue, which is obviously the reason why the tax exists at all, what we’ll see is that the taxes will follow the money . They’ll find a way to increase the tax on the use of electric vehicles.