The first pickup truck with an all-aluminum body rolled off Ford Motors’ assembly line Tuesday. The F-150 is about 700 pounds lighter than Ford’s previous model. As a result of its lighter weight, the new F-150 is expected boast a 20 percent increase in gas mileage. If the aluminum F-150 proves to be a market success, it could significantly change the auto industry, spurring competitors to create lighter weight, more fuel-efficient trucks. However, the new F-150 is also more costly to manufacture, so Ford is taking a risk with the new model. The market will decide its fate when it starts hitting showrooms next month.