They use two completely different engines dude. The Miata uses its Mazda 2.0 Skyactiv-G engine (naturally aspirated 16 valve DI dual cam) and the Fiat uses a multi-air 1.4 liter(Turbo, single cam). They don’t even use the same transmission. The Miata is a new tranny as of 2015 and the Fiat uses the old 6 speed from…