Well, it's common practice for the US car magazines to do a standardized skidpad evaluation to determine maximum G force whenever a car is tested.
It's not an increasing spiral as you suggested but instead it's typically a fixed circle the car must follow.
Car and Driver magazine uses a skidpad with a diameter of 300 feet and typically the results for street vehicles range from .70G for 4X4 SUVs to nearly 1.00 for exotic sports cars. No mention of the speed on the skidpad is ever made.
Of course there's a lot more to handling that driving fast in circles.
