Perhaps we have. Or so argues Ilan Berman here. An excerpt:

“With more than two-thirds of its budget and some 80 percent of its export earnings tied to its oil and natural gas sectors, Iran is the epitome of an energy economy. Gasoline, however, is its weakest link. Iran, though a major oil exporter, suffers from an acute shortage of refining capacity. As a result, 30 percent or more of Iran’s annual consumption of gasoline is fueled by purchases of the product from a select group of foreign suppliers. And because it is, U.S. policymakers have reasoned, targeting Iran’s gasoline dependency would dramatically ratchet up the costs of Tehran’s nuclear endeavor, and ultimately could change the strategic calculus of Iran’s ayatollahs.

The world is about to find out whether this logic is correct. That’s because Iran’s imports of refined petroleum from abroad have plunged precipitously since the passage of gasoline sanctions some three months ago.

In July alone, Iran’s gasoline acquisitions reportedly fell by half, and since then imports have constricted still further. Experts now estimate that between August and September, Iran imported just 12,000 tons of refined petroleum from abroad – less than one half of an average tanker shipment, and as much as 80 percent less than the previous month’s total. Iran’s gasoline trade, in other words, is imploding.

Officials in Tehran insist that this is intentional. Earlier this month, Masoud Mirkazemi, Iran’s Oil Minister, triumphantly declared that the Islamic Republic had attained “gasoline self-sufficiency,” and was no longer dependent on foreign refined petroleum. More recently, Iranian Vice President Mohammad Reza Rahimi announced that his country had boosted its refinery capacity by some 50 percent, and as a result had stopped importing gasoline altogether.”