1g is simply acceleration equivalent to that of gravity 9.81m/s^2

therefore to accelerate from 0-200km/hr (0-55.555m/s) in 1.3 sec

Average acceleration= V/t = 55.555/1.3 = 42.7346m/s^2

convert to g's is /9.81 => 42.7346/9.81= 4.356g