This is cool. Though it feels like it should be a Basic tier, like Bob's basic belts, while still allowing the oil driven drones later, for a mid game boost, while still allowing you to access the drones in early game. Then all we'd need is nuclear powered drones.... thinking face

Would love to but that would require to create a set of recipes for each kind of fuel and every item, which is a lot of overhead.

is it possible to remove this mod from a savegame safely ? then we could simply use both mods in earlygame to have any transport drones available (to not need starting with a standard beltbus, especially also in games where oil production is delayed for some time), and later in midgame remove this mod when we feel comfortable to run the drones on petrol ...

a special case: in fantario, electric power (and thus also normal steam engines) are delayed until after space science.
to solve this problem, and maybe also for normal use in earlygame, would it be possible somehow to power these drones with anything else, preferably wood or coal, or maybe optionally have some new "wood gas" engines or a new earlygame assembler that makes woodsyngas from wood or coal, to be used exclusively for these drones (to not mess up any other production chains or combinations with other mods) ?

see https://de.wikipedia.org/wiki/Holzgas (with pictures of many vehicles that use this woodgas) and https://en.wikipedia.org/wiki/Wood_gas : first vehicles with woodgas were built in 1901, and at the end of WW2 there were more than half a million of woodgas vehicles, even until the 1950s, and also for heavy trucks in siberia where wood was available but normal fuel/diesel was not yet reliably available. when using woodgas, the gas from 3kg wood can be used instead of 1 liter normal fuel/diesel.

edit/ps : besides the vanilla recipe, there are several mods for coal liquifaction, making oil from coal, etc. maybe this could be combined somehow with this mod, giving a really earlygame option (right from the start, or at least after researching assembler2 to be able to have liquid input/output) to make one type of special gas (instead of steam) that is not compatible with oil/petrol/etc (to keep the oil/sulfur/plastic/etc production for midgame as in vanilla), but have some new gas instead of petrol to be used for these drones only ? optionally extending the compatibility of such a new assembler beyond wood and coal to also use other items from other mods (like pellets, saplings, etc) then shouldn't be too complicated either :-) and in midgame, this mod could be removed, or the new assembler could be extended to convert petrol/oil/etc to woodgas too ??
crazy ideas maybe, but maybe you get some hint what could be done to make it interesting and more widely useful :-)

lol ... just after writing this, i saw that darkfrei has just updated a mod to use steam for assemblers. might be interesting to convert the entire factory to be steam powered .... (or woodgas powered?)