Note that an ICE can be built (or possibly reconfigured) to run on alcohol, oil, hydrogen gas, or almost any other flammable liquid or gas. They're not limited to worlds with petrochemical deposits or imported gasoline. Virtually any planet with a breathable atmosphere and able to support even limited agriculture will be able to produce fuel for ICE engines, and many without such amenities will still be able to manufacture it by utilizing local chemical deposits to produce flammable liquids.
My assumption is that many vehicles will have a drivetrain mechanically coupled to the engine (as per the modern day "car"), while others will have an engine which drives a generator, and run off stored electrical power using electric motors (gas-electric hybrids). The former will be simpler and cheaper to build, but have more restrictions as to fuel type, while the second could have different engines (reciprocating piston, gas turbine, fuel cell, or small fusion reactor) dropped in easily during final assembly, depending on what types of fuels are available at the location where it will be used. Even if the engine itself is fusion in that individual vehicle, the overall vehicle design and level of performance would still be considered "ICE".
As shown by Tesla, the latter type, with electric motors, can out-perform a mechanically coupled internal combustion engine for brief periods, limited primarily by battery storage capacity. Having a small or modest-sized "engine" to recharge the batteries would allow far greater duration in the field than a purely battery-powered design which would need frequent breaks for recharging.