How does the running cost of the Ertiga CNG variant compare with that of its electric alternative?

As electric vehicles become more popular, and the government is pushing for cleaner transportation, the long term viability of CNG vehicles like the Ertiga CNG is becoming a subject of debate. The Ertiga CNG is famed for its low running cost, but electric vehicles are starting to beat it on overall efficiency and environmental impact. How do the Ertiga CNG running costs compare to newer electric alternatives in the same price segment? What are the hidden costs or benefits of either one of those options compared to the other? We will see how the real world economics of running an Ertiga CNG in India compares with that of an electric vehicle.