Ford Motor Co. F 3.15 % reaped the benefits of its costly F-150 truck revamp, doubling income in its first quarter and posting a North American operating margin rivaling those returned by luxury brands. The Dearborn, Mich., company is among auto makers benefiting from record U.S. light-vehicle demand and low gasoline prices, a trend fueling sales of the most profitable models on dealer lots. As sales of trucks and sport-utility vehicles soar, Ford is receiving a strong profit and sales boost from product redesigns rolled out since Chief Executive Mark Fields took over in mid-2014. The No. 2 U.S. auto maker by sales also is gaining steam in China, earning more than $400 million last quarter in a country where it historically has lagged far behind General Motors Co. GM 0.87 % and bigger […]