WASHINGTON — The Environmental Protection Agency (EPA) will move ahead Friday with a rule requiring cleaner gasoline and lower-pollution vehicles nationwide, amounting to one of President Obama’s most significant air-pollution initiatives, according to people briefed on the decision.

The proposed standards would add less than a penny a gallon to the cost of gas while delivering an environmental benefit akin to taking 33 million cars off the road, according to a senior official.

Oil-industry officials said the cost would be at least double the administration’s estimate and could add up to 9 cents to a gallon of gas.

The proposed standards, which had been stuck in regulatory limbo since 2011, would reduce the amount of sulfur in U.S. gasoline by two-thirds and impose fleetwide pollution limits on new vehicles by 2017.

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While gasoline sulfur does not pose a public-health threat, it hampers the effectiveness of catalytic converters, which, in turn, leads to greater tailpipe emissions. These emissions contribute to smog and soot, which can cause respiratory and heart diseases.

The regulations are supported by environmental advocates, state regulators and automobile companies, who would prefer uniform sulfur standards. Oil-industry officials and their congressional allies say it will cost up to $10 billion to upgrade refineries and an additional $2.4 billion in annual operating costs.