A traditional open two-seater, the TR3 is an evolution of the company's earlier TR2 model, with greater power and improved braking.

[8] Although the base car is an open two-seater, an occasional rear seat and bolt-on steel hard top were available as extras.

This OHV straight-four initially produced 95 bhp (71 kW; 96 PS), an increase of 5 hp over the TR2 thanks to larger SU H6 carburettors.

[9] Front suspension is by double wishbones, manganese bronze trunnions, coil springs and telescopic dampers, with an optional anti-roll bar.

[citation needed] The rear suspension comprises leaf springs, a beam axle, and lever arm dampers.

It has a convertible hood that snaps on and off and removable side curtains, allowing very low doors with padding for the driver's arm to rest on.

In 1959 other changes were made to the car, including raised stampings under the bonnet and boot hinges and under the door handles, as well as a redesigned rear floor section.

For the "TR3A" it reported a 0–60 mph (97 km/h) time of 12.0 seconds, power output of 100 bhp (75 kW) at 4800 rpm, observed kerb weight of 2,090 lb (950 kg) and fuel consumption of 28 miles per imperial gallon (10 L/100 km; 23 mpg‑US).

The TCF series has a fully synchronised transmission and a 2138 cc version of the Standard wet-liner engine with a 9:1 compression ratio.

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

[20] 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.

[25] Yet another suggests that the Beta project was begun because Triumph lacked the financial resources needed to tool up to produce the new TR4 body.

Work started on the car at Triumph's Capmartin Road (aka Radford) plant, and was later transferred back to their Fletchamstead North site.

[27][24][26] In addition to its wider chassis and modified bodywork, the TR3 Beta shared its fully synchronised gearbox, rack-and-pinion steering, and larger engine with the TR4.

[28] The TR3 was campaigned in races, hill climbs, and rallies across Europe and North America, with several outright, team, and class victories to its credit.

In response, Triumph competition manager Ken Richardson had steel hard tops bolted to 100 TR3s, homologating the new sports car as a "grand touring" coupé, the GT class still permitted to race on French public roadways.

[13] TR3s were campaigned in the RAC, Monte Carlo, Circuit of Ireland, Alpine, Liege-Rome-Liege, International Tulip, Scheveningen-Luxembourg, Tour de France, Douze Heures de Huy, Lyon-Charbonnieres, Acropolis, Chimay National, and Corsica rallies, among others, achieving numerous outright, team, and class victories including six "Coupes des Alpes" awards.

With its robust engine and rugged reliability, the TR was a popular competitor in continental hill climbs, such as the Ollon Villars and Eberbach Bergrennen, and endurance races like the 12 Hours of Sebring and the Mille Miglia.

[31] The Jopp/Stoop TR3S ran as high as seventh place overall before being forced to retire due to mechanical difficulties with just over an hour remaining in the race.