Launched in 1969 with the 150bhp fuel-injected TR5 engine, it was given a softer tune early in 1973 and the car undoubtedly had sacrificed some of its original performance for the sake of greater refinement. In the USA, traditionally Triumph's best market for its TR range, Triumph's engineers were unable to make the fuel- injected engine meet the new exhaust emission standards, and as a result had to fit a twin-carburetor engine with only 104bhp into Federal TR6s, making the cars no faster than their TR4 ancestors. Nevertheless, it was by far the most successful TR before the TR7, with nearly 95,000 built.