When, as and if CNG becomes an economic alternative, private industry will address the opportunity.
Until then, government needs to stay the hell out of it!!!
Granted, this would have to be a private initiative, but the government is going to have to remove a LOT of roadblocks to let this happen.
As it happens, there are some parts of the infrastructure already in place, with all the natural gas lines already criscrossing the country, so the basis is already there.
If the machinery for refueling vehicles can be put in place without overwhelming and highly redundant approval protocols being placed as an obstacle, that part would also be streamlined.
As to the vehicles themselves, starting a clean design as a new manufacture would be the best option, but for all the older vehicles now out there, a retrofit to use CNG as a fuel is currently a pretty expensive deal. For instance, there would have to be solid reliable fittings for the storage of CNG on board, controlled means of fueling the engine, and the engine parts (valves and cylinder heads, in particular) would have to be modified to take full advantage of the potential output of CNG as a fuel source.
Compression can be raised quite a bit, because natural gas has an equivalent octane rating of 130+, and also a much hotter burn, which makes demands on exhaust valves and exhaust pipes, requiring either replacement with a more durable part, or engineering the power and exhaust cycle to take advantage of something called “adiabatic cooling”, in which the exhaust temperature is somewhat lowered because of the rapid expansion of the burned fuel-air mixture. Engineers know these terms, and in fact, a number of automobile engines have already been built that take advantage of this fact of thermodynamics, enabling them to run with little or no coolant left in the system.
Doable. And for an economically favorable cost, if the various regulatory agencies do not build up a trumped-up set of regulations to make this enterprise fiscally infeasible.