BEDFORD, Pennsylvania — For the briefest of moments, a line of vintage Rolls-Royce automobiles chugged along the curving Cumberland Road. They passed over the Cumberland Run a handful of times and wound themselves down the mountains, away from Pennsylvania and toward the city of steeples, Cumberland. The sight gives the bystander a moment to imagine what it looked like in the early days of American road tripping. These 1922 Rolls-Royce vehicles,…