Autocross Rules & Classing

This page is the definitive source for the rules and vehicle classing applicable to the MCO Autocross Championship.


These rules should be read in conjunction with the applicable CASC General Competition Rules (GCRs), as identified in the Autocross Championship Supplemental Regulations. All competitors are expected to familiarize themselves with the applicable rules.

Should amendments be made after initial publication of any of the documents below, the documents linked here will be updated, replacing the out-dated versions.

MCO Members are invited to propose revisions to the documents for the consideration of organizers and to facilitate continuity in the organizer community.  Proposals can be submitted to Autocross Directors.

The versions here will be treated as the authoritative version should there be any discrepancy with any other version.

MCO Supplemental Regulations



Everyone needs a helmet and it needs to be appropriately certified. If you don’t have one, rentals are available at local events. Details on appropriate helmets can be found in Section 4.5 of the CASC Autoslalom Regulations. Snell 2000 helmets are no longer accepted.

Helmet rental cost is $20.00 (HST Included) – please bring cash (exact change appreciated) to the event.  Your helmet entitles you to the helmet for the whole day of the event.

Participation by Minors

Any prospective participant under the age of 18 must contact [email protected] in advance of registering. Ideally, this contact should precede registration cut-offs by two weeks.

Vehicle Classing

MCO uses an in-house classing system to place competing vehicles in one of six classes – Prepared, A, B, C, D and E classes. The MCO classing system incorporates elements of the Sports Car Club of America (SCCA) National Solo Rules and the yearly PAX index, which is a relative index of performance in autocrossing, much the same way a handicap rating is given in the game of golf. These values are used to establish the base classification of cars. This base classification is then impacted by changes made to a car, such as modifications to the engine, suspension, driveline, vehicle weight reduction and the type of tires used.

MCO competitors must calculate their MCO vehicle class each year since PAX classing values change each year, and the MCO classing worksheet is adjusted to match with those changes.  Changes to the PAX values can cause your car to change classes from the previous year.  Please make sure to complete your calculation for your MCO class using the current classing worksheet before the beginning of each season.

The first thing to do when classing your car is to locate your vehicle in the current SCCA National Solo Rules Quick Reference Sheet – Street Category by Manufacturer. Make sure you’re looking at the latest rules and reference sheet for the current year.

NOTE: Car numbers are unique and restricted to a single class. This means that if you have used number 25 in one class, you cannot use it in another class. If you are switching classes, you will need to choose a new number. Please contact [email protected]org to get this done.

Classing Worksheet

2022 MCO Autocross Classing Worksheet v1.0

Use “File – Make a Copy”, or Download a copy in order to be able to enter your data

Should you have any questions about modifications to your vehicle that you feel are not covered in the documents above, you can pose you question to the MCO Classing Committee on their Facebook page here or by contacting the Autocross Classing Committee at [email protected]