Natural Gas Cylinders in the trunk are an option too. I saw them in Korea and Asia being used where petrol is too expensive.
Like you building with deep cycle batteries oneself is a decent option. If you live in the city and can get forty miles range it ought to be enough to allow you to keep your old vehicle rather than purchasing a new one outright.
Place I worked for had a propane conversion on a 80s Chevy truck with a 350. That thing was a slug on propane.
I’m not moving to the city so I’m going to need at least 60 miles. I’ve also thought about getting an old Mercedes with the million mile engine. Supposed to be good for running biodiesel.
IF this phase out of fossil fuels actually does happen, it will be decades from now and I would think diesel would be the last to go. Electric heavy equipment, 18 wheelers and large farm tractors ain’t gonna cut it. One could just get a vehicle with a small diesel. Volkswagen makes them. Chevy Colorado would be my pick. Gotta have a truck though I’d prefer full size. All depends on future fuel prices.
I have a little subcompact tractor. 1980 Mitsubishi that has mechanical injection and it would probably run on biodiesel with some modifications. Biodiesel has to be heated in cool weather. It already has a block heater so the engine can be made nice and warm. Guess I’ll need solar panels/batteries to run the heaters though. LOL
We actually lived off grid for 5 years. Two while searching for land and three after we got the land. Ran off of a small solar panel set up. Charge controller went out 3 days before electric service was installed. Inverter not too long after that and the golf cart batteries are shot but they made it 7-8 years which is higher than average. It was kind of cool hearing the neighbors complain about the electric being out the previous day. We were clueless to that and were likely on the internet the day before. We had phone/DSL 3 years before we had electric service. Ran it off the inverter as it takes very little power.
I do want to get the solar panels set up again. Need 4 golf cart batteries($500) and a charge controller($200). Already replaced the inverter. The router and cordless phone would go back on solar and we still have LED lighting that currently runs off an RV converter, until the electric goes out. The converter is also a charger so even just having batteries would give us a day or two just running LEDs and internet.