US retail sales rose in August for a third month in a broad advance, rounding out a summer of resilient spending. Motor vehicle sales rose at a slower pace, even though some economists expected it to be a drag on the overall figure. The retail sales report showed so-called control-group sales — which feed into the government’s calculation of goods spending for gross domestic product — climbed 0.7 percent in August, so far indicating a healthy third quarter. The retail sales figures largely reflect purchases of goods, which comprise roughly a third of overall consumer outlays. Spending at restaurants and bars, the only service-sector category in the retail report, advanced 0.7 percent after declining in the prior month.