Which maths are you doubting?
radial (centripetal) acceleration = r * (angular velocity)^2.
170 rev/sec * 2pi = 1068 radians/sec. r = 45cm, so a = 510000, or 50000g after some rounding to be conservative.
10500 RPM was also claimed; divide by 60 to get the same 170 rev/sec (again, rounded for journalistic use).
A number not cited in the article: 1068 rad/sec *r = 480 m/sec linear velocity of car. But a m/sec is 2.23 MPH, so 1070 MPH. That's only a little higher than the target speed record, which is averaged over a mile or more.
