The gestation period for a new Volvo model has always been rather languid. Back in the 1950s, when tailfins were making annual progress toward low earth orbit, Volvo was cranking out PV444 and 544s.

It’s been 70 years since Volvo began selling cars in the United States. In September 1955, Volvo unveiled to the public the PV444 prototype, a maroon coupe with whitewall tires, in the Swedish ...