liquid fuel …

… should not be wasted, and used only where it can not be replaced by other means e.g. airplanes/spacecraft where every pound of weight counts! everything else could carry a few more pounds of weight, e.g. a car that has 100lb more because of high-pressure-tanks for CNG looses a bit of efficiency, or a train that has to carry one car extra devoted to CNG but still weighs a few million lbs … or even ships, one could replace highly unhealthy sulfuric oil with CNG tanks (and install sails!)(old fashioned but cheap!) and not loose significant storage room/weight. exceptions could be small craft (mopeds), tractors, emergency vehicles etc (like a firetruck should carry water NOT fuel)

analogy: it’s easier to loose a few pounds of bodyfat than spending a few thousand $ on a bicyle that is lighter …