Aluminum may knock some weight off, but the raw material is more expensive than steel. I don't think the mileage increase would offset the cost. Ford and the rest of the manufacturers have already priced themselves out of the market for the average working person. If the automakers are willing to permanently settle for sales of 8-9M vehicles annually it could happen. But aluminum is more susceptible to stress cracks than steel. Anyone who is familiar with the aviation industry and airplane maintenance knows this first hand. I certainly wouldn't want to have to deal with stress cracks in a roof panel, cowl panel, or someplace that would cause water to leak into the vehicle. And at $40K and up MSRP you can't consider F150's throw-away vehicles.