Below is a great image we found at the Detroit Public Library showing King George VI and Franklin Roosevelt in a convertible vehicle heading down, what probably is, Pennsylvania Avenue during the former’s official visit in 1939.
Packard Co. file photograph of a 1939 Packard three-quarter right front view, top folded, during a parade, crowds lining street, police officers on motorcycles next to car, another car in background, seven other men walking behind car. Inscribed on photo back: “1939 Packard twelve, model 1708, seventeenth series, 12-cylinder, 175-horsepower, 139-inch wheelbase, 5/6-person special parade car, built for White House fleet. Official reception parade in Washington D.C. for their majesties King George VI (in lead car with President Roosevelt) & Queen Elizabeth (in second car with Mrs. Roosevelt), during 1939 state visit.”
Source: Detroit Public Library