Highway Funding Equity Act of 2005 - Amends Federal highway law to revise Federal highway minimum guarantee requirements.
Requires the Secretary of Transportation, for each of FY 2005 through 2009, to allocate among the States amounts sufficient to ensure that the percentage for each State of the total apportionments for the fiscal year for certain Federal-aid highway programs (including the basic minimum guarantee under this Act) equals or exceeds 95 percent of the ratio that the estimated gas tax payments attributable to highway users in the State paid into the Highway Trust Fund (HTF) bears to such payments attributable to highway users in all States (with a specified exception for any State having a population density of less than 50 individuals per square mile).
Provides for: (1) the programmatic distribution of funds above $2.8 billion for certain Federal-aid highway programs; (2) the apportionment of the remainder of funds to the States; and (3) required adjustments where the sum of State percentages exceeds 100 percent.