Its becoming more difficult to get a sense of the interaction between the US and Iran about Iran's nuclear program because so much is obviously going on behind the scenes.
Iran has around 7,000 centrifuges in Natanz, about 5,000 operational and 2,000 in preparation. This is the same configuration in place since May and there can be no explanation other than that Iran has decided not to put in line the centrifuges that are in place and ready for vacuum testing or to install new centrifuges. One possible explanation for Iran not putting new centrifuges in line is that the US does not know how many centrifuges Iran has in reserve, that could be diverted to a different undeclared enrichment facility if, for example, the US bombed Natanz. But not activating already declared centrifuges is clearly a voluntary gesture on Iran's part. Another gesture is that Iran has expanded IAEA access to Natanz and allowed inspections of Arak had been suspended when the IAEA board reported Iran to the security council.
Possibly there is an agreement coming into view that will preserve Iran's right to enrich uranium and will not harm Iran's long term aspiration for a status of nuclear weapons capability comparable to those of Japan, Brazil or the Netherlands.
Once again, I'll point out that Iran having a nuclear weapons capability like that of Japan or Brazil is completely legal under the NPT. Iran sees the UNSC resolutions demanding Iran cede its rights as invalid just as Israel would see a UNSC resolution demanding it sign and ratify the NPT as another resolution to be ignored. In fact, for the UNSC under the pretext of protecting international peace and security, to demand Iran ratify the additional protocols and stop enriching uranium while not demanding that Israel ratify the NPT, dismantle its actual nuclear weapons, and stop military operations against neighboring civilian populations is reasonably seen in Iran as clear hypocrisy that decreases the legitimacy of the security council more than it decreases the legitimacy of Iran's nuclear program.
Hossein Askari and Trita Parsi wrote an interesting article for the New York Times that gasoline sanctions may actually benefit Iran from Iran's perspective by giving an excuse for ending expensive subsidies on gasoline and increasing the incentives for conversion to natural gas-run automobiles.
Anyway, Iran maintains the option of putting more centrifuges into production and increasing the rate of enrichment. That it has not is an indication that contrary to reports, Iran believes progress is being made on resolving the nuclear issue in a way acceptable to Iran's leadership. I wish I understood better what form any progress is taking, but nothing is being published.
Even assuming that a gasoline embargo would be effective, what would be its result? Consumption would decline by 40 percent and government revenues would go up, because no payment would be needed for gasoline imports.If Tehran allowed the reduced supply of gasoline to be sold at a price that would equate demand to supply, the price would increase to a level that would eliminate the subsidy, meaning no subsidy for imported gasoline and no subsidy for domestically refined gasoline. The government would have more revenue to spend elsewhere. The sanctions would have done what Tehran has wanted to do for years and the government would not be held responsible!