One thing that comes to mind: Gasoline/Diesel. You never stated what kind of engine you’re using, but you might be simply out of gas.
Another possibility is that your batteries aren’t full enough. A car needs a certain percentage of power inside the batteries, which seems to depend on the Engine used. I believe I saw reports of 2 5% car batteries not being enough to start a car, so I recommend at least 15% ; could be even more, as I said, seems to depend on the Engine in use.
If you want to have a new car, there are several options:
a) You could spawn one. The debug menu has the option to spawn >any< vehicle from the jsons, from small unicycles to trucks. (and all the modded stuff too.). Those cars also have full gas and power, as far as I remember.
b) Build a new one: For that, you preferably mutate you first - theres an option in the debug menu for that. search for ‘debug’ and you find several mutations which will negate hunger/thirst, smell, you can be invisible, and there is one which lets you build stuff without the need for tools or ingredients - so you can build whatever you want.
If you don’t want to be indestructible while building, just use the spawn-menu and spawn the parts you need and start building.
