Hybrid HOV Access Act of 2004

Hybrid HOV Access Act of 2004 - Amends the Federal Aid Highways program to require a State agency that has jurisdiction over the operation of a HOV facility to establish the occupancy requirements of vehicles operating on the facility.

Requires such agency to permit motorcycles and bicycles to use the HOV facility.

Permits a State agency to restrict use of the HOV facility by motorcycles or bicycles (or both) if it certifies to the Secretary of Transportation that such use would create a safety hazard.

Prescribes guidelines under which a State agency may permit use of an HOV facility by: (1) public transportation vehicles and high occupancy toll vehicles; (2) inherently low-emission vehicles and low emission and energy-efficient vehicles; and (3) advanced lean burn technology vehicles.

Permits tolls to be charged on a HOV facility on the Interstate System.

Requires a State agency that allows low-emission and energy-efficient vehicles to use a HOV facility to certify to the Secretary that it will establish: (1) a continuous monitoring, assessment, and reporting program regarding the impacts such vehicles may have on the operation of the facility and adjacent highways; and (2) an enforcement program that ensures the facility is operated in accordance with this Act.

Directs the Administrator of the Environmental Protection to issue: (1) a final rule establishing certification requirements for low emission and energy-efficient vehicles and advanced lean burn technology vehicles; and (2) guidance on methods for determining whether a vehicle meets the fuel efficiency standards required to qualify as a hybrid vehicle.