Triumph

In 1956, Triumph began planning a successor to the TR3. The TR4's new ponton body, designed by Giovanni Michelotti, does away with the cutaway door design and sloping boot lid of the previous TR's. The TR4 offered an optional hard top consisting of a fixed glass rear window with integral rollbar and a detachable centre panel made of aluminium on the first 500 units and steel on subsequent cars. It was the first such roof system on a production car, predating the Porsche 911 Targa by five years. The TR4 used the same four-cylinder engine that powered the TR2 and TR3, but with displacement increased from 1,991 cc to 2,138 cc. 

In 1965, the TR4A superseded the TR4. Although appearing nearly identical to the TR4, the TR4A was equipped with a significantly revised chassis, independent rear suspension and a wider front and rear track, as well as numerous changes to the exterior trim and interior fitments. The TR4A used the 2,138 cc engine from its predecessor, with power raised to 104 hp. Production lasted until 1967, with the arrival of the new TR5.