General Motors Corp. announced on Nov. 27 that Monsanto Co. has placed the first 50 orders for its new Chevrolet Silverado full-size pickup trucks that run on a blend of ethanol and petrol.GM, the world's largest automaker, said it will begin offering the "flex fuel" option on the 1500 series Chevrolet Silverado and GMC Sierra full-size pickup trucks with the 5300 Vortec engine in the first quarter of next year at a cost of around $250.The trucks can run using E85, a blend of up to 85 percent ethanol and gasoline, or using pure gasoline. Ethanol, typically made from corn products, produces less air pollution than gasoline and reduces the dependence on foreign oil, according to GM.GM also offers the Chevrolet S-10 and GMC Sonoma compact pickups, and Chevrolet Tahoe and Suburban and GMC Yukon and Yukon XL sport utility vehicles with E85 compatibility."We expect the demand in this area to grow," said GM spokeswoman Denise Sedman.Demand for ethanol blend vehicles has been limited by the higher cost for the fuel and its limited availability. E85 is currently found at just over 100 filling stations across the United States.GM receives a credit toward federal requirements on fuel economy -- helping it meet government mileage mandates -- regardless of whether the trucks ever burn ethanol.According to Sedman, an estimated 1.2 million vehicles in the United States are equipped to run on the E85 ethanol blend. However, many industry analysts say most of these vehicles likely will never be fueled with E85.