ATLANTA – As employee-pricing programs for new vehicles spread in July, so, too, did the weakness in used-vehicle values. The Manheim Used Vehicle Value Index, which measures wholesale prices on a mix, mileage and seasonally adjusted basis, fell in July for the third consecutive month and at a faster rate than in either May or June. The Index now stands at 108.8, down 1.7 percent from June, but still up 2.2 percent from its year-ago level.