First Generation: 1967-1969
Pontiac's car hit the streets about 6 months later than it's sibling, the Camaro, upon which it was based. Although the firebird was a late arrival to the scene, Pontiac made up for the delay by offering an array of models and options. In the following paragraphs, I will try to point out the major differences between the various Firebirds, both visually and through the mention of certain equipment. First off, the first generation cars were available in two basic body styles: the 2 door coupe and the 2 door convertible. I don't think you have to be an automotive engineer to see the difference in the two body styles. Both firebirds can be broken down into two major groups: the OHC-6 cars and the V-8 cars.
Pontiac's overhead-cam inline 6 engine was certainly ahead of it's time. Producing 165-175 horsepower, the base OHC-6 could be backed by a manual or automatic transmission and proved to be an economical engine. A more muscular version of the OHC-6 was the Sprint-6, which featured better mechanicals and a 4-bbl Quadrajet carburetor. The Sprint-6 produced 215-225 horsepower was included in the "Sprint" package with side striping and unique engine call-outs on the hood and rocker panels.
Since the Firebird was born in the middle of the "muscle car" era, the V-8 engine and option packages were prolific on the first generation cars. Other than the engine displacement call-outs on the hood, there was no real visual differences between the OHC-6 and the V-8, with three notable exceptions: the "H.O." option, the "Firebird 400" and the 1969 "Trans Am". The "H.O." package which had either the 326 or 350 V-8 received side striping similar to the "Sprint-6" versions. The "Firebird 400" had a unique twin scoop hood along with specific grilles. A further option on the "Firebird 400" models was the Ram Air set-up which opened the twin scoops in the hood to allow fresh air into the Ram Air cleaner. The "Trans Am" option offered in 1969 was radically different from any other Firebird, with a unique hood, fender air extractors, a rear wing, and a unique paint scheme featuring twin blue stripes over a white base color with Trans Am decals on the fenders and rear wing.
Second Generation: 1970-1981
As with the first generation cars, the second generation Firebirds came late to the scene hitting the showroom floors in February of 1970. This model was a radical change from the 1969 and earlier cars. They were heavier, wider, longer, and lower than the first generation cars. Engine choices remained fairly consistent though except that the OHC-6 was replaced with the Chevrolet inline-6 (L6), or in later models, the Buick V-6. Pontiac offered four distinct models of Firebirds: "Firebird", "Esprit", "Formula", and "Trans Am" and actually changed the VIN numbers to reflect each model. As a result, the second generation cars are best broken down by models rather than engine like the first generation cars. Also, only one body style was available which was the 2-door sport coupe (the convertible didn't make it back until the Third Generation 1991 cars).
The standard Firebird featured a flat hood, no spoilers and very little chrome accents, and standard 14" wheels. The standard engine was the Chevrolet 250 cu.in. V-6 (L6) until 1977 when the Buick engine took over. Also in the late 70's, "special" Firebirds were fitted with either "Red Birds" or "Yellow Birds" on the hood and usually featured better interiors as well.
The Esprit was the luxury firebird model which featured upper level trim, sport mirrors, wheel trim rings, larger rocker panel moldings and an "Esprit" logo on the sail panel. All Esprit's received custom interiors and the larger V-8 engines until 1977 when the Buick V-6 took over again.
The Formula model was the "Street-Brawler" of the second generation cars. The Formula received the power drive train of the bigger brother, the Trans Am, but kept the body of the Firebird. The main difference between the Formula and the Firebird was the hood. The Formula had a twin scoop hood (like the first generation Firebird 400's) which was functional on some models. The exceptions were some 1973 and 1974 models that were equipped with the "Super Duty" 455 V-8's, which utilized the shaker scoop like the Trans Am's, and the 1980 and 1981 models that were equipped with a turbocharged 4.9 liter V-8, which utilized the offset scooped hood like the Trans Am's. Early second generation Formulas (pre-1976) received Formula emblems while later cars (beginning in 1976) received unique Formula decals of varying designs. The rear spoiler, rally wheels, gauge packages and the like were not standard on the Formula, but were "extra-cost" options available.
The top of the line Firebird was the Trans Am, with it's front and rear spoilers, fender flares, fender air extractors, shaker scoop, and extra decal graphics. The second generation Trans Am's went through a change throughout the 70's. The earlier cars (70' to 74') were hard performance cars carefully blending the "European" styling with "All American" horsepower. As the 70's progressed and emissions became more stringent, the Trans Am lost a little of it's performance while still keeping it's racy bodywork. The performance was removed slightly while the ride became softer, the interiors became more luxurious, and more convenience options were added. Amazingly though, sales actually increased as the years went by while hitting it's peak in 1979 when over 120,000 models rolled off the assembly lines. The Trans Am was now Pontiac's flagship model of the 70's.