The GT6 project started in the mid-’60s when Triumph realized they needed a coupe version of their popular roadster. However, just putting the roof on Spitfire wouldn’t do the trick. They needed to extensively re-engineer the car and add a more powerful engine for the chassis to cope with the added weight of the coupe body style. So Triumph engineers installed a 2.0-liter six-cylinder engine with 106 HP, providing the GT6 with more power and performance than the similar Spitfire (via Auto Express).
The GT6 was officially presented in 1966 and discontinued in 1973 after around 45,000 examples. The GT6 was never as popular as the Spitfire, but it was arguably a better car and a cool-looking alternative to all other sports coupes on the market.