1. Abbreviation for Subaru Technica International, the tuning and motorsports arm of Subaru. Analogous to Mercedes' AMG and Ford's SVT.
2. A model of the Impreza that has been extensively modified by STi. The name STi is used because of the length of the car's real name, the Impreza WRX STi.
3. The poor man's supercar, one which can outrun a Porcshe Boxster in the 1/4 mile and can rip up snow and gravel due to its all wheel drive.
4. EVO killer and the fear of all things Mitsubishi.
"That EVO on the highway got owned by my STi."