DEARBORN, Mich. — It was hardly planned this way, but Ford Motor on Tuesday began building its most fuel-efficient pickup ever, just as gas prices kept dropping to their lowest level in years.

Despite the timing, Ford is betting that its new aluminum-body F-series pickup truck will be a hit with consumers and an important step toward achieving new government fuel standards.

“Even with gas at $3 a gallon, fuel economy is still very important to people,” William Clay Ford Jr., the automaker’s executive chairman, said at the ceremonial introduction of the pickup at Ford’s Dearborn Truck assembly plant.

Mr. Ford said that gas consumption was the largest area of consumer dissatisfaction in the purchase of pickup trucks.