Iran's lawmakers voted on Wednesday to pump $3 billion into subsidies that keep gasoline cheaper than mineral water for the Islamic Republic's gas-guzzling motorists.
Keeping petrol cheap is a vital political concern for Iran's ruling populist conservatives despite increasingly unmanageable congestion and pollution in big cities.
Iranians pay about 10 cents per litre.
Parliament voted to withdraw some $2.6 billion from the country's rainy-day Oil Stabilisation Fund (OSF). Iran is strictly only meant to tap these dollar reserves when oil prices slip beneath budgeted levels.
"Some additional 3,638 billion rials ($402 million) will be taken from domestic resources at the national oil company," Parliament Speaker Gholamali Haddadadel told the parliament session which was broadcast live on state radio.
With record oil prices, it is estimated that the OSF should clock up a surplus of $24 billion in the year to March.
Despite being the world's fourth biggest crude producer, Iran has to import about 40 percent of the 60 to 70 million litres of gasoline it burns each day because of a lack of refinery capacity.
The huge dollar withdrawal approved on Wednesday will go towards paying for those imports in the year to March 2006.
The parliamentary vote must now be approved by the Guardian Council, Iran's constitutional watchdog.
But many are realising that populist measures to feed the gasoline habit are increasingly unsustainable.
The Central Bank has warned that unwarranted raids on the OSF stoke up inflation, already running at about 15 percent.
The International Monetary Fund and ratings agencies have recommended Iran lift its petrol prices to global levels.
Despite voting for continued subsidies, parliamentarians have also pencilled in a debate on the issuing of rationing smart cards and the creation of a dual pricing system so imported gasoline will sell at a more realistic level.
Iran is also expanding a credit scheme to encourage people to take old cars to scrapping centres.
The success of these measures to tackle rampant consumption in such a huge import market is being closely watched by Asian and European traders.