General Motors Co. is accelerating efforts to field a largely aluminum-bodied pickup truck by late 2018, under pressure from federal fuel efficiency standards and archrival Ford Motor Co., according to people familiar with the matter.

The No. 1 U.S. auto maker recently locked-in supply contracts with Alcoa Inc. and Novelis Inc., which are now working to increase their aluminum sheet production to supply the next-generation GM pickup, the people said. Aluminum sheet for automotive bodies is in such high demand that companies...