Each THSCC class category other than Open Class is scored as if it were a single class, with the times from different vehicles normalized by the handicap index from each vehicle's class.

Example: An ND Miata, classed in C Street, may choose to compete in the Novice Class category with C Street classing. In this case, the driver's runs will be scored against all other drivers in the Novice Class category by multiplying each driver's fastest time with the handicap index assigned to their respective class. If the driver instead selects the H Street Open Class category, he/she will be scored only against the other H Street Open Class competitors without using the multiplier.

Open (Regular) Class
Most drivers compete in one of the many "Open" Classes. Drivers here generally are fairly experienced autocrossers, running on special racing tires or using street tires with a treadwear rating of 200 or higher* for Street Classes.

Novice (NOV) Class
Competitors are eligible for novice class if they have less than one (1) year of autocross experience with any club. Once entered in Novice, you may compete in Novice for the remainder of the season, and (if you are a club member) compete for a year-end Novice trophy. In Novice Class you will be competing only against other drivers with the same amount of autocross experience that you have. You are not required to run in Novice Class even if you are eligible.

Pro Class
The best drivers in the club enter in Pro Class for 2 reasons:
1. to compete directly against each other regardless of class, and
2. to give drivers in the Open Classes a better chance to win.
If you have been dominating your class and have been scoring consistently in the Top 10 Indexed Times, you are strongly encouraged, though not required, to run Pro Class.

Also, if you are a visiting Pro Class caliber driver, you are requested to run in the Pro Class instead of a regular Open Class so as not to upset regular club members' Open Class season points races.

Senior Racers (SR) Class
Another indexed class. Minimum age: 60 human years.

* The treadwear rating is a number printed in small letters on the sidewalls of your tires. It appears together with the Traction and Temperature ratings.