Proponents of tougher auto fuel-economy standards plan to use a new war-related argument, according to a Wall Street Journal story by Jeffrey Ball: that energy-security concerns, not just environmental issues, justify mandating less-fuel-thirsty pickupsb and sport utility vehicles. Automakers, meanwhile, hope to delay Congressional efforts to limit sales of their most profitable vehicles by urging lawmakers to wait for the results of a more detailed study by the National Highway Traffic Safety Administration (NHTSA) of the best way to stop the recent drop in the average mileage of new vehicles in the U.S. The slide in average mileage of U.S. vehicles is largely due to the popularity of pickups and SUVs, according to industry analysts and environmentalists. The latest round in the fuel-economy debate comes as auto makers are trying to sustain or regain profits, and U.S. consumers are continuing to buy SUVs and pickups in large numbers, in part because gas prices have plummeted from high levels this summer. The Senate Commerce Committee will hold a hearing Dec. 6 on whether to toughen the federal auto-mileage standards far beyond a small increase the House called for in its own energy package this year. The hearings follow Senate Republicans' rollout Dec. 5 of an energy package that stresses increased efficiency and seeks to boost supply without drilling in Alaska's Arctic National Wildlife Refuge.