The Triumph GT6 is a 6-cylinder fastback version of the Spitfire, styled by the Italian designer Giovanni Michelotti, and produced over 7 years from 1966 to 1973. The classic car was constructed and marketed following the Spitfire fastbacks (four-cylinder engine) that were victorious in their class during the 1965 24 hours of Le Mans. During its seven years of production, more than 40,000 units of the British car were sold, though these days they are becoming rarer to see with the value of the GT6 increasing markedly over the last 3 years.
History of the Fastback
The Triumph GT6 was based on the hugely successful sports car, the Triumph Spitfire, that was designed by Italian Giovanni Michelotti in an effort to compete against the likes of the Austin Healey Sprite and MG Midget . Michelotti had become famous for his car designs. Not only had he designed the Spitfire for Standard-Triumph, but models for other famous makes like Ferrari, Maserati, and Lancia.
In 1963, Harry Webster, the Director of Engineering of Triumph, initially asked Giovanni Michelotti to design a GT version of the Spitfire 4. By the end of the year, the studio returned their new bright red prototype of the car to England for evaluation. The bright red prototype, registered 4305VC, was driven by Triumph test driver Fred Nicklin from Turin to Coventry,
Standard-Triumph management was extremely impressed with the styling of the new GT prototype. But, they were unhappy with the increased weight of the car. The new body shell caused the car to perform unacceptably, at least when fitted with the standard 70 cu in (1,147cc) engine. For the time being, plans were dropped for the production of the new Spitfire GT4.
The new Michelotti fastback design for the Spitfire GT4 did, however, encourage Triumph to adopt it for their 1964 racing program. In 1965, fiberglass copies of the GT4 fastback were grafted to fit onto race-modified competition Spitfires.
The new aerodynamic shape proved much superior to the regular body shape, and the car performed successfully during the racing season. At the finish, the GT4 fastback had come in 13th place overall and first in class at the Le Mans 24 Hour race, easily defeating the MG Midgets, the company’s main rivals.
With the Spitfire GT4 fastback’s competitive success and continued commercial success of the Spitfire, Standard-Triumph re-evaluated its shelved plans for a GT version of the Spitfire (Spitfire GT).
To improve on the underperformance of the prototype, the 4-cylinder engine was replaced with a more powerful inline 6 that had originally been built for the Standard Vanguard Six and also used in the Triumph Vitesse. With its new 6-cylinder engine, the car performed much better with Michelotti’s sleek but heavier body style. It was a tight fit getting the 1998cc six cylinder engine into the Spitfire’s engine bay, but it was achieved by developing a complex cooling system and a large hood power bulge.
With the more powerful 2.0 liter (1,996cc) engine and some further refinement, the car was introduced to the public in 1966 as the Triumph GT6 (dropping the “Spitfire” prefix) to emphasize its GT styling and new 6-cylinder engine.
With its sleek fastback design and a rear hatch that opened, the new GT6 earned the nickname of a “poor man’s Jaguar E-Type“.
The Standard-Triumph marketing department advertised the new GT6 as having been developed from the “race winning Le Mans Spitfires,” so it could capitalize on the aesthetic similarities between the GT6 and the Le Mans Spitfires.
In truth, however, the Le Mans cars and the new GT6 were based on two entirely separate development programs. Despite the differences, the company’s marketing spin became so successful. Most of the buying public continued to erroneously believe the Le Mans Spitfires were actually the same cars as the new Triumph GT6.
Design of the GT6
The 6-cylinder engine was tuned in the GT6 to develop 95 hp (71 kW) at 5000 rpm, and torque of 117 lb.ft at 3000 rpm. Its top speed was reported as being 106 mph and could accelerate from 0–60 mph in slightly under 12 seconds, somewhat better than their primary competition, the MGB GT.
The new engine was also quite smooth and tractable, in contrast to the 4-cylinder B-series engine in the MG that produced almost the same power rating in twin carburetor form but at a higher rpm.
With the increased power and larger engine, several changes needed to be made in the original Spitfire mechanics. The car required mounting a new radiator slightly further toward the front of the engine bay. The gearbox needed to be a stronger unit, so they used a four speed manual gearbox from the Triumph Vitesse.
The front springs were upgraded to handle the extra weight, and the overall unladen weight was 1,904 lb (864 kg).
The interior of the new GT6 featured a gloss lacquered, walnut veneered dashboard that housed a full complement of instruments that were chrome rimmed and the switches were toggle type. A heater and carpets were standard equipment with the interior comparing nicely to the competition.
The one main criticism about the new car was the old swing axle rear suspension that had been used in the Spitfire and copied from the Triumph Herald.
The swing-axle could be tolerated in the conservatively driven Herald. But, was more difficult to handle during offensive driving around corners, although only when lifting off the throttle mid-corner at great speed. The lower aspect of the tire located on the inside corner tucks inward which results in a jacked-up suspension. Unfortunately, the increased weight of the engine in front of the car made the problem even worse.
The car was bitterly criticized in the U.S. for its poor handling, where the company had an important export market, and Triumph had traditionally been very strong. Similar criticism was also leveled at the Vitesse saloon, which shared the same engine and handling properties.
The production of the Mk I occured during July 1966 – Sept 1968 with 15,818 units produced.
Triumph GT6 Mk II
Production: July 1968 – Dec 1970. Units: 12,066
It was clear to Triumph that they needed to sort out the old swing-axle rear suspension in order to improve the handling of the GT6 to maintain their reputation in the U.S. In 1968, they responded with the introduction of the GT6 Mk II model, branded in North America as the GT6+.
The problem with the rear suspension was improved significantly by using reversed lower wishbones and Rotoflex driveshaft couplings. This tamed the handling and turning problems of the Triumph GT6, the main problem with the Mk I.
The Mk II received some additional changes for 1969, including raising the front bumper along with the Spitfire Mk III to conform to new government crash regulations. A revised front end was added, and side vents were added to the front fender and rear pillars of the car. Another change involved adding rear-tinted glass with an integrated heating element.
Under the hood, the engine of the upgraded Vitesse MkII was utilized that delivered an output of 104 hp with a new cylinder head, camshaft, and manifolds. The top speed increased to 107 mph, with acceleration from 0–60 mph reduced to only 10 seconds.
To save on costs, the interior door levers and window cranks were identical to the units in the TR6 model. The interior was upgraded to a non-reflective matt lacquer veneered dashboard with the gauge’s surrounded by black rims and non-reflective rocker switches.
Both the Mk I and Mk II had steel wheels fitted as standard however wire wheels were possible as a factory-fitted optional possibility when buying a brand-new vehicle.
Triumph GT6 Mk III
Production: Oct 1970 – Dec 1973, Units: 13,042
The MKIII was the most gracious and performed best of all the three GT6 models. The entire body shell was revised to match the most recent changes to the Spitfire Mk IV featuring a cut-off rear end, smoother front, and recessed door handles. The hood resembled the MKI GT6 apart from the addition of eight angled louvers on the side of the front fenders. On the driver’s side rear fender, a lockable gas cap was fitted, as opposed to the rear in the previous model.
The interior cabin provided more comforts such as increased padding throughout, the inclusion of reclining seats (provided after chassis number KC 75,030), and the addition of a face-level ventilation system.
Only a few changes were made to the mechanics of the car until the 1973 model was introduced near the end of its production life. The suspension was upgraded once again to a less-expensive “swing-spring” design that was identical to the layout of the Spitfire Mk IV. Additionally, the interior seats were changed to cloth from Vinyl in 1973.
The engine power and torque for the Mk III were essentially the same as the Mk II but with better aerodynamics. The car could reach a top speed of 112 mph, and accelerate from 0–60 mph in 10.1 seconds.
The Mk III came fitted with steel wheels only as wire wheels was not a factory option.
End of the GT6
Ultimately Triumph, along with many other British auto manufacturers, were unsuccessful in being able to re-engineer their cars to meet the more stringent U.S. DOT and EPA standards. Consequently, manufacturing of the Triumph ended only after 3 years following the first Mk III rolling out of the factory.
In total 40,926 Triumph GT6 were produced over 7 years, though with time it is estimated there may be fewer than 8000 left in the U.S.
Specifications of the GT6
1966 Triumph GT6 Mk I Specification
Bore x Stroke
74.70 x 76.00 mm
95 bhp @ 5000 rpm
Suspension – rear
Transverse leaf spring and swing axle rear suspension
0-60mph: 12 seconds
Valuations of the Triumph GT6
Over the last three years, the Triumph GT6 has appreciated well with a Mk I in excellent condition increasing from an average value of $13,000 in 2018 to over $20,000 in September 2020 (see below).
The Triumph GT6, being a true sports car, was and still continues to be raced successfully throughout the world.
In an effort to promote its sports cars, Triumph divided its SCCA racing into two groups in the 1970s. Bob Tullius and his Group 44 team would cover the East Coast races, while Kas Kastner, focussed on West Coast races with Kastner-Brophy Racing.
Group 44 Inc – Bob Tullius
In 1960, Bob Tullius bought a Triumph TR3 for his wife, but she seldom drove the car. Instead, he decided he might enjoy racing the car and took it to racing school. He won the graduation race and relished driving the car fast so much that he began to race the Triumph in regular sporting events.
In 1961, in his first four races, Tullius was able to finish in first or second position and won the National SCCA Points championship.
In 1962, Tullius asked Triumph to give him a Triumph TR4 to race as he was leading in national points and Triumph wasn’t getting the publicity for their TR4. Although he was knocked back initially, he did end up with the TR4.
In his first race at Lime Rock, he took second place. But, on his next outing at Lake Garnett, the car crashed and was totaled.
Triumph refused to replace the car, so Tullius and Diehl purchased two more wrecked TR4s and put together a replacement car using the assorted parts from all three wrecked cars.
In 1963, Tullius decided to pursue motorsports professionally after his supervisor at Kodak, where he worked, told him he had to choose between his day job and racing. He chose racing and soon became the principal driver working under Kas Kastner, Triumph’s North American Competition Manager, where he appeared in his first 12 Hours of Sebring race. He would go on to win six SCCA championship races in the factory TR4.
Tullius established his own racing team in 1965, called Group 44 Incorporated, to pursue his chosen vocation fielding Triumph TRs and Spitfires and eventually became one of America’s most successful racing teams. The Group 44 cars were easy to recognize as they were all painted green and white, prepared impeccably, and won countless victories.
In 1969, the Group 44 Triumph GT6+ driven by Tullius, Mike Downs, and Brian Fuerstenau, secured the E-Production SCCA National Championship at the American Road Race of Champions (AARC) in Daytona Beach, Florida.
In 1970, the car won the D-Production pole position at the very first SCCA Runoffs at Road Atlanta. It was leading the race when it retired with transmission problems.
The GT6+ was found in 2005 as a “barn find”, with the crew chief from Group 44 Inc, Lanky Foushee, confirming its identity.
A comprehensive restoration was conducted with the car returning to the near-exact representation of its appearance in the winner’s circle at Daytona in 1969.
In 2009, the car won the Amelia Award at the Amelia Island Concours d’Elegance before participating in the Monterey Historics that August.
The Triumph GT6 was undoubtedly an attractive, 60s two-seater fastback that complemented the Spitfire in Triumph’s successful export lineup. A classic benchmark design that endures today in the hearts of sports car enthusiasts.