OK, My question doesn't address the smoothness of a higher-number of engine cyl. My question deals more with the additional weight of a trike vs. the MPG average. If a 6 cyl. 1500cc engine was powering the same weight trike as a 2 cyl. engine of the same cc size... which should get the better gas milage? I would think available torque/HP numbers would play an important part because of how 'hard' the engine would need to work to pull the trike weight, but wouldn't the additional engine weight also effect the numbers? My Roadstar engine is 1600 cc in two cyl. An older Goldwing engine at 1500 cc has 3 times as many pistons putting out (about) the same displacement. Add 'water-cooled' weight and any other weight factors & I would think the MPG would suffer for that extra weight. Please shed some light on this logic.