That's when the long lines and frustration began.
School bus driver Feroz Ahmad in the southern port city of Karachi said he waits in line for CNG for up to four hours each time he goes to the pump. His minibus can also run on gasoline but that would be more expensive.
"I can't afford petrol because of the high price. I would have to increase the pickup and drop-off charges" for the children he takes to and from school, he said.
Before the recent price change, CNG cost about 30 percent less than gasoline. Before that, CNG was even cheaper in comparison, but the government had managed to bring CNG prices up bit by bit to wean consumers off it through a variety of means, including raising surcharges on station owners.
"We are the 27th largest producer of gas in the world, and we are number one in CNG cars. So either those 26 countries are mad or our policies are bad. And I think it is the latter," said Hussain, the petroleum minister, in an interview with The Associated Press. "We have wasted our gas, basically."
The CNG station owners have built up an infrastructure that spans the country and are fighting back. Paracha, the head of the CNG association, said if all the vehicles on the road started using gasoline instead of natural gas, there would be a huge increase in pollution, and it would be extremely expensive to import all the fuel.
"This will have a very, very bad impact on the economy," he said.
Most other countries that use natural gas for private vehicles have an abundance of natural gas, said Leslie Palti-Guzman, an energy analyst at the Eurasia Group. Iran, for example, also uses natural gas extensively for private vehicles in part because international sanctions on its nuclear program make it impossible to export natural gas.
Other countries tend to use it more for things like fleets of buses or taxis, Palti-Guzman said. Then they can reap the environmental benefits of using natural gas, which tends to burn cleaner than oil or coal, without having to build an entire network of CNG stations around the country.
But getting Pakistani drivers to use more expensive gasoline is politically difficult, especially with an election coming up soon.
Ask anyone in the lines in Pakistan's largest cities who is to blame for the current crisis and the list is extensive: the CNG station owners for allegedly gouging customers, the government for failing to keep prices in check, even the Supreme Court for failing to find a suitable compromise.
Few seem aware of the larger problem of Pakistan's rapidly dwindling natural gas supplies.
"I really don't know what's wrong with the gas supply," said Nayaz Khatak, a government worker in Islamabad waiting to fill up his car. "There is no shortage as such."
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Associated Press writers Adil Jawad in Karachi, Zaheer Babar in Lahore and Asif Shahzad in Islamabad contributed to this report.