>In all probability they will keep making & selling the stuff to the millions of users of petrol and diesel cars still on the road after the ban on the sale of NEW cars comes into effect (if it does).
Agree. My previous post wasn't worded well, so it could be read as you did.
To be clear, I didn't and don't expect all filling stations to shut or petrol refining to stop on 1st January 2031.
However, it's likely to be chicken-'n'-egg? Fuel at filling stations around here (rural) is expensive already; who's going to bet against HMG withdrawing the subsidy that stops rural filling stations being even more expensive? So more are likely to close; here, that could easily mean a round-trip of over a hundred miles to buy petrol. Ain't gonna happen imho. Especially as there are already free electric charging points within ten miles of me. They'll only proliferate, even if The Wee Krankie and her mates can't figure out a way to subsidise more installations.
Demand'll reduce even where petrol is still sold, which'll make it more expensive, which'll reduce demand, etc., etc.
Long journeys, I've used the www to plan fuel stops for several years already, currently either because supermarket fuel is considerably cheaper than service-area fuel (for the car) or I prefer putting high-octane in the bikes. Continuing to use infernal confusion engines, I expect to have to continue that planning, eventually just to find any fuel.