Lack of capital to fund development was partly relieved by the sale of Triumph's tractor division to Massey-Harris of Canada.

A long overdue refresh of their small sedans was further complicated by the departure of chief stylist Walter Belgrove over a disagreement with the direction of the redesign.

[4] After being introduced to Giovanni Michelotti, Triumph managing director Alick Dick invited the Italian designer to produce a concept car for the British company.

[5] Built by Vignale on an unmodified TR3 chassis, Michelotti's TR Dream Car incorporated many styling cues from contemporary American practice, including tailfins, a full width grille, lidded headlamps in the tops of the front wings, and a two-tone paint treatment.

[8][7][6] The Zest received a full-width body style, with headlamps that were inset from the sides and set high in the grille to stand above the bonnet, which was shaped into cowls over the lamps.

Around this time Triumph's Competitions department was working on a new high performance engine with the development label 20X, later named Sabrina after contemporary British actress Norma Ann Sykes, the 20X is an inline four cylinder engine with dual overhead camshafts, and was expected to develop 160 hp (119 kW).

The new shape, named Zoom, was a full-width body, with tall doors having wind-down windows, and headlamps moved to the tops of the front wings.

[7][9] The Zoom body was used for the three Triumph TRS race cars fielded at the 1960 24 Hours of Le Mans, which were powered by three 20X DOHC engines.

The cars were revised and entered again in the 1961 race, where they finished ninth, eleventh, and fifteenth overall, and claimed the manufacturer's team prize for Triumph.

[12][7][4] The TR4's new body, produced in Triumph's Speke factory, does away with the cutaway door design and sloping boot lid of the previous TRs.

[14][15] The TR4 offered an optional hard top consisting of a fixed glass backlight with integral rollbar and a detachable centre panel made of aluminium on the first 500 units, and steel on subsequent cars.

Additionally, the optional Laycock de Normanville electrically operated overdrive could be selected for second, third, and fourth gears, effectively providing the TR4 with a seven-speed close ratio gearbox.

[7] TR4s were also assembled from Complete Knock-Down (CKD) kits in Mechelen, Belgium and Borgo Panigale, Italy, the latter in a factory owned by Ducati.

[19][1] American Triumph dealers were concerned that buyers might not accept the car's updated styling, so a brief special run of TR3s, commonly called TR3Bs, was produced for the US market in 1961 and '62.

[20] A small number of TR4s were put to use as "Fast Pursuit Cars" by police departments in places such as Manchester City and the Southend-on-Sea Borough.

[24][25] The TR4 had a number of racing successes in America, primarily through the efforts of Californian engineer Kas Kastner and his top driver, Bob Tullius.

In 1961 the TR4 with commission number CT 7L, driven by George Waltman and Nick Cone, won first in class and thirtieth overall at Sebring.

Soon after the TR4 was introduced, Kastner and with Mike Cook from the advertising department at Triumph in New York City convinced the company to provide three new TR4s to race in the 12 Hours of Sebring in 1963.

An estimated 25% of TR4As sold in the US were not equipped with IRS but instead reverted to a live axle system similar to the TR4's on a slightly modified TR4A chassis.

A total of 43 Dové GTR4 and GTR4A fixed head coupés were produced at the direction of L. F. Dove Ltd., an auto dealership in Wimbledon, London.

[33] Conceived as a more weather-proof alternative to the drophead coupé TR4, the Dové provided a way for Dove Ltd. to enter the market for GT automobiles.