Understand the basic draw back with dedicated CNG, HCNG or Hydrogen Vehicles. By any way, emissions from these Vehicles are far better than that from Fossil Fuel Vehicles (Petrol + Diesel). Hydrogen is a far better fuel then CNG, HCNG and even Fossil Fuel. Only reason, they fail to make it as primary fuel is the size of fuel tank and Mileage it can give in return. 55kg CNG cylinder on 1300c.c car will give you average of 140 km, similarly HCNG will give an average of 125 km with same size cylinder whereas 50Liter petrol tank can easily give you a mileage of 600 km plus in single tank so this basic reason why world prefers fossil fuel over others. Now, you would not want to refuel on highways after every odd 150km that is why you don’t find any dedicated CNG vehicles otherwise its more feasible choice then fossil fuel vehicles. I hope, this answers your question.
We live in most hideous part of world. I don’t mean to criticize my nation but definitely do criticize our leaders. Everywhere in world, Nations wants to enforce public into using CNG as secondary fuel because of cheap availability and better emissions but here in Pakistan once we already have 90 % vehicles running on CNG, they are discouraging this. Government can pay millions to import fossil fuel ( Diesel + Petrol) but they don’t want to import Natural Gas from Iran which by every mean is cheaper and has better profit margin for government.
I got the chance to meet "Renounced Politician A" on informal gathering (Details are irrelevant) where I asked him the same very question whereas he replied that politicians have their money invested in countries like USA, UK and Europe that’s why they get blackmailed easily and end result is we suffer in worst of ways first corruption and secondly safety of corrupt money from countries like UK, USA and Europe by listening to their agenda. End result is that we get looted and on top denied with a facility.