Its a gimmick in the sense that a car’s power capability is first reduced only to be increased again by the press of a button.
For example a car without Sports Mode has an engine which is capable of producing 140hp. The same car is given a button and the power without that button pressed is reduced lower than what was its full capacity. Sports mode not a magic mode that an engine capable of producing 140hp uses telepathy to gain more power than what the engine can produce max so therefore: It is a gimmick
A 1.8 doesn’t become a 2.0 with such a mode. It stays a 1.8 with same engine output which it was capable of