LIVONIA, Mich. - General Motors Corp. has put two-and-a-half times as much aluminum as steel into the Precept, its first high-mileage supercar concept model which foreshadows the prototype auto GM is expected to unvell before 2004 to meet its commitment to the government-industry Partnership for a New Generation of Vehicles (PNGV).

Equipped with more than half a ton of lightweight aluminum components, including several parts of the hybrid electric propulsion system, the Precept is a 5-passenger car capable of providing approximately 90 miles per gallon with diesel fuel, equivalent to about 80 mpg with gasoline.

he first detailed account of the body structure (spaceframe) and body shell applications for metals in the Precept, which was introduced early this year, was given by Thomas L. Lobkovich, manager of advanced body engineering for GM, at the 21st annual Automotive Design and Fabrication Seminar here sponsored by the Automotive and Light Truck Group of the Aluminum Assocaiton.

Lobkovich said that the aluminum body structure of the Precept weighted 152 kilograms (335 pounds). The structure is made up of 192 parts joined by 600 rivets, 1,600 spot welds and 15 meters of metal inert gas (MIG) welds but no adhesive bonds.