IMHO the current system of re-usable 'fuel cans' makes fossil/biofuels WAY more hassle than they are worth... being unstackable makes them almost pointless as a method of energy transfer given their limited EU capacity. Please don't mention lap-packs, batteries, uranium cells, Electrolyzers or any other form of portable energy - I know they exist, but I don't want to use them.
If balance is an issue (altho with the advent of high output nuclear, I can't see it), then make fuel more expensive to craft - 10x the plant material, or 4x the coal, whatever it takes - but please bring back my beloved diesel from the old IC days!