That was partly due to two fewer selling days for radio’s biggest ad category. GM, Ford and other manufacturers reported lower U.S. vehicle sales for May due to sluggish demand for sedans and those two fewer selling days. General Motors’ sales fell 18 percent, Ford was down 6 percent and Toyota’s sales dropped 10 percent compared to 2015. Volkswagen’s sales were down 17 percent. Fiat Chrysler and Subaru saw slight increases. Hyundai’s sales jumped 12 percent.