Heavy Duty Hybrid Vehicle Research, Development, and Demonstration Act of 2008 - Directs the Secretary of Energy to establish a competitive program to provide between three and seven grants of up to $3 million in each of three years to advance research and development and to demonstrate technologies, including plug-in hybrid technology, for advanced heavy duty hybrid vehicles (vehicles with a gross weight of between 14,000 and 33,000 pounds that are fueled, in part, by a rechargeable energy storage system); and (2) conduct research into alternative power train designs for use in advanced heavy duty hybrid vehicles.
Amends the United States Energy Storage Competitiveness Act of 2007 to direct the Secretary to conduct an applied research program on energy storage systems to support vehicles with a gross weight over 16,000 pounds.