1975 was a turning point in American automobile production. Since the defeat of the Arab countries in the Yom kippour war in 1973, rising oil prices cause the loss of the "Muscle-Cars" age. Despite this, the Firebird progress commercially. Late 1974, it only remains on the U.S. market for the 2 +2 sports cars Camaro, Firebird and expensive Corvette. This is also from that year that the pollution standards have imposed catalytic converters. Although almost all cars produced from 72 run on unleaded gasoline and despite the emergence of the HEI ignition, the catalyst and the compression ratio down continue to make these engines certainly cleaner, real calves. For who says fewer emissions also said fewer horses.
Side style and although the model 75 'is an evolution of 74', it is characterized by its rear window "panoramic". It was designed to reduce the dead angle that procured the previous versions. It was originally planned for 1970, but severe cuts in the budget have delayed its development in manufacturing. We also see the change in the location of the front turn signals which pass into the front grille "as fog lamp."
The speedometer is also subject to some changes, including graduation intentionally limited to 100 mph/160 kmh, but the dual graduation in miles and kilometers per hour. U.S. officials believed at the time that if a meter indicating a speed limit, drivers are not tempted to try to drive as fast as the last line (what they were naive!).
The system HEI (High Energy Ignition) allowed to increase the ignition voltage from 25 to 35,000 volts and include the coil to the distributor, but also the abandonment of the ignition contact breaker that leaves room for an electronics module more reliable, efficient and maintenance free. The advance is itself always centrifuge and vacuum. A result of a more powerful spark, the spark plug type is new (R45 and R46TSX) and the gap of the electrode is revised upwards from 0.40"(1 mm) to 0.60" (1.52 mm). Maintenance intervals have been spaced to reduce the costs. Thus, replacing the spark plugs were all recommended every 22,500 miles and oil changes every 7500 miles. Finally, the 455ci returns on August 75 T/A but with a power of 200hp, it unfortunately has nothing in common with its predecessors ...
Always with the objective to reduce emissions, and in addition to the HEI, gasoline was also new. The rate was 87 octane, which is the current SP95 went hand in hand with the catalyst. All engines of this year had only a single exhaust system, probably for economic reasons, since otherwise it would have to use two catalysts.