Gasoline Price Stabilization Act of 2005

Gasoline Price Stabilization Act of 2005 - Sets forth circumstances under which the President may issue orders and regulations to stabilize prices for wholesale and retail gasoline to levels at or below levels prevailing on March 1, 2004.

Amends the Energy Policy and Conservation Act to include, among prerequisites to a drawdown and sale from the Strategic Petroleum Reserve, a presidential determination that a severe price increase resulting from an emergency situation is likely to cause a major adverse impact upon a state or regional economy.

Expands the scope of "severe energy supply interruption" to encompass a reduction in supply that is substantially caused by conduct that lessens competition (or tends to create a monopoly) by: (1) at least one foreign country or international entity; or (2) at least one producer, refiner, or marketer of petroleum products.

Directs the Secretary of Energy to establish mandatory minimum inventory levels of crude oil and petroleum products in order to limit the impact of unexpected supply disruptions on wholesale and retail prices.

Amends the Mineral Leasing Act to repeal the authorization to export Alaskan North slope oil.

Amends the Internal Revenue Code to: (1) impose an excise tax on the sale in the United States of any crude oil, gasoline, or other taxable product equal to the applicable percentage of the windfall profit on such sale; and (2) allow a tax credit for the cost of any qualified passenger vehicle purchased by the taxpayer during the taxable year.

Amends the Clayton Act to: (1) prohibit certain oil industry mergers; and (2) place a moratorium upon large petroleum and crude oil mergers.

Amends federal transportation law to increase the average fuel economy standards for passenger automobiles and light trucks.

Requires federal agency heads to manage vehicle procurement in a manner that results in specified increases in the average fuel economy of the federal fleet of vehicles.