The 1990 model year was ended on December 31, 1989. In reality, this had nothing to do with the Firebird itself. Because Chevrolet lost the "IROC" rights for the flagship Camaro at the end of the calendar year, they chose to begin the '91 model year on January 1st, 1990. To keep up with the Camaro, Firebird planners chose to debut the '91s at the same time.

1990 models received very few changes from 1989. The base coupe had a slightly larger, 140hp 3.1 litre MPFI V6 as the standard engine, replacing the 2.8. Also new was a driver's airbag. Trans Ams were no longer available with the throttle-body-injected 305 V8 as standard...the 200hp 305 TPI was the new standard T/A engine.

Standard, base coupe: LH0 3.1 litre MPFI V6, 140hp

Optional base coupe, standard Formula: L03 305 TBI V8, 170hp

Optional Formula, standard Trans Am: LB9 305 TPI V8, 200hp (auto), 225hp (5 speed)

Optional, Formula and T/A, standard GTA: B2L 350 TPI V8, 235hp