GTI may refer to:
Automotive Grand Tourer Injection, a car model variant Maserati 3500 GTI, the first GTI car ever, from 1961 Volkswagen Golf GTI, the first GTI hot hatch Peugeot 205 GTI, a famous hot hatch Proton Satria GTI, a sportier variant Suzuki Swift GTi, Suzuki GTi variant GTi Engineering, an auto racing team
Other uses Atlas Air, ICAO code GTI Galway Technical Institute, a third level educational facility in Galway, Ireland Gas Technology Institute, an American non-profit research and development organization Gerakan Tani Indonesia, a peasants organization in Indonesia Gires–Tournois interferometer, a component for femtosecond lasers Global Terrorism Index, a report published annually by the Institute for Economics and Peace (IEP) Global Tiger Initiative, a conservation effort funded in part by the World Bank Global tilted irradiance, the solar irradiance on a tilted plane GrafTech, a graphite manufacturing company, NYSE symbol GTI Grațianite, IMA symbol Gți Grid-tie inverter, an apparatus to convert DC electrical (solar, wind) energy to AC and deliver it back to the grid GT Interactive, a video game publisher and distributor GTI Club, a racing game originally released for the arcades in 1996 by Konami GTI Mortsel, a vocational secondary school in Mortsel, Belgium Guilford Transportation Industries, a transportation company Pokémon Mystery Dungeon: Gates to Infinity, a 2012 game in the Pokémon Mystery Dungeon series