Mack, Volvo, Hino Diesel Truck Sales and Service in Maryland and Virginia | Baltimore Potomac Truck Centers Baltimore Potomac Truck Center is a family owned dealership group operating five full-service commercial truck dealerships representing Mack, Volvo & Hino Baltimore | Potomac Truck Centers offer parts, service, and sales of heavy and medium duty trucks for Mack, Volvo,and Hino trucks. With factory trained technicians and large inventory of new and used trucks, our six locations serve Greater Baltimore, Western Maryland (Hagerstown), Northern Virginia (Gainesville), and Washington, DC (Bladensburg).