On a side note: BattleTech actually used 'mechs powered by internal combustion engines, and did it seriously. At a serious disadvantage, though -- something like double the tonnage, and a lot more volume, for the same power output. Generally only found on Periphery worlds where fusion reactors were so hard to come by that even the worth-their-weight-in-platinum BattleMechs had to make do with lower-tech powerplants.
Had issues with providing enough power for beam weapons, too. Although there wasn't any penalty for missile boats.
Had issues with providing enough power for beam weapons, too. Although there wasn't any penalty for missile boats.