Found this and I agree.
'GT' means 'grand touring' in English; it refers to a vehicle that has supposedly been designed for high-speed highway travel, hence the 'grand' in touring.
In reality, any auto maker can put a 'GT' badge on its vehicles, but unless the engine, trans, and suspension are actually designed for high-speed travel, the car won't be any faster/sporty with the 'GT' in its name or stuck on a fender