Triumph TR4 poster. The Triumph TR4 was introduced in September 1961 to replace the TR3. The bodywork was designed by the Italian stylist Giovanni Michelotti and featured a stylish "bulge" in the bonnet to accommodate the twin SU carburettors. A 2138cc engine gave a healthy average of 25 mpg and a top speed of 110 mph. The TR4 encompassed wind-up windows and a decent sized boot. (available at Art Of Motoring).