I have read in several posts about CNG batteries, do not know what special thingy these are. But I have a concern that batteries and self starter motor of a CNG-fitted car have a reduced life due to constant starting and restarting while queuing up at CNG filling stations. Suppose you have 15 cars in queue in front of you, so 15 extra starts and stops after two or three days as compared to petrol driven cars. I know many people would say it's a cheaper trade off. lol.