The base engine becomes the 3.1-liter V6, a driver air bag changes the steering-wheel/interior presentation, and this is the final factory kit to use IROC-Z before the 1991 Z28 return.
It is the last IROC-Z model year. The corpus's explanation of an intentionally short model year is plausible secondary research but was not established by a primary production calendar in this pass.
The powertrain and identification notes below preserve configuration and model-year boundaries rather than treating every 1990 Camaro alike. Ratings use the measurement convention of their period, and visual cues are only a starting point: the VIN, factory labels, drivetrain identifiers, and surviving documentation should agree.