The big story in Egypt tonight isn’t the presidential election, or the upcoming verdict in former president Hosni Mubarak’s murder and corruption trial. It’s gasoline, or a lack of it.

Motorists across the country are dealing with a major fuel shortage, the third of the year and by many accounts the most serious. Dozens of cars were queued up tonight outside a state-owned Misr Petroleum station in the upscale Zamalek neighbourhood, seemingly one of the few stations in Cairo with fuel. The line of cars brought traffic on 26th of July Street, one of Zamalek’s major thoroughfares, to a near standstill.

A taxi driver pushing his cab through the queue - the car’s tank was bone-dry - said he’d spent more than two hours driving around the capital, looking for gasoline. Tempers were running high: Drivers nearly came to blows with an attendant when he tried to block one of the entrances to the station.

A few blocks away, a Mobil station was a relative oasis of calm. Signs on the gas pumps proclaimed them out of order the bored attendants said they were out of gasoline, and they didn’t know why, or when supplies would be restored.

Traffic on the airport road was backed up for nearly a mile this afternoon because of gasoline shortages. Egyptians on Twitter reported shortages in other neighbourhoods, including Heliopolis, Nasr City and Ma’adi, and on the desert highway that connects Cairo to Alexandria.

Why is Egypt running out of gasoline? Depends on who you ask. Some energy officials say they’re still supplying the same amount of gasoline, and they chalk the shortages up to panic buying and hoarding.

Others told the state-owned Al Ahram today that they’re running out of cash to buy gas (which is heavily subsidised by the Egyptian government). They blame the finance ministry.

Another theory is smugglers: The government buys gasoline and sells it to contractors, who supply it to gas stations many people believe the contractors are skimming off a portion and selling it on the black market, at much higher prices. (This is the reason for widespread shortages of subsidised butane cylinders, another major problem since the revolution many Egyptians rely on those cylinders for cooking fuel.)

Meanwhile, the newspaper owned by the Muslim Brotherhood’s Freedom and Justice Party blames the shortages on Ahmed Shafiq, one of the two contenders in the presidential runoff. The shortages create chaos, the newspaper argued, which helps Shafiq, who’s running on a platform of “stability.”

Fayza Aboulnaga, the always-colorful minister of planning and international cooperation, has promised to resolve the shortages "within a few hours," but the government's pledges don't seem to inspire much confidence among drivers who have spent their Thursday evenings queuing for gasoline.