Ford's sales increased 21.9 per cent in May compared to a year earlier, its sixth straight gain of more than 20 per cent, the US carmaker said today as it continues to rebound strongly from a rough 2009, dpa reported. But rival General Motors remained the largest US manufacturer, selling 223,822 vehicles in May, a 16.6-per-cent gain from last year. Ford's sales on the month totalled 196,912. This month last year, GM was headed for bankruptcy with the help of billions of dollars in government loans. Ford was the only major US carmaker to survive the recession without needing protection from creditors or emergency federal aid. GM left bankruptcy under the majority control of the Obama administration and has since been working to shut down four loss- making brands. The four remaining "core" brands - Cadillac, GMC, Buick and Chevrolet - posted a 31.8-per-cent gain in sales in May. Other carmakers like Toyota and Honda were to report US sales later Wednesday.