Checking the process I find I was right.
The “petrol from air” technology involves taking sodium hydroxide and mixing it with carbon dioxide before "electrolysing" the sodium carbonate that it produces to form pure carbon dioxide.So you first obtain sodium Hydroxide, available from any babbling brook in England, and mix it with CO2, presumably extracted from the atmosphere normally using high pressure compressors and heat transfer apparatus, then electrolyze the mix using electricity from unicorn farts, to produce carbon dioxide of a higher purity than the stuff you bought from Air Liquide, and water vapor.
Hydrogen is then produced by electrolysing water vapour captured with a dehumidifier.
The water vapor in turn is condensed and electrolyzed using power from a coal-fired plant to produce Hydrogen and Oxygen. The Oxygen is disposed of and the hydrogen and carbon dioxide are mixed at very high pressure and probably temperature and coaxed to combine into Methanol which in turn is run through a high pressure and temperature device to convert it to octane which is then poured into your gas tank.
I don't doubt for an instant that the process will work, but the cost in energy and process machinery and operation does not look to me to be particularly efficient. Perhaps when the price of ordinary petrol reaches $50/gal.