I knew a guy that had a pickup converted to propane back in the 80’s and he just loved it. I would think this would be a lot better.
It would be . . . if propane were cheaper than gasoline. Which it isn’t.LNG requires so much infrastructure that it’s only fit for long-haul truck fleets.
I see CNG as being competitive with electric vehicles - same sort of range limitation, but substantially cheaper fuel than gasoline. And, realistically, you are better off relying on NG than on electric power.