Unusual Vehicles/Engine Changes

Some vehicles require special smog inspection services. 

Referees can inspect Specially Constructed Vehicles (kit cars), vehicles with engine changes, modified vehicles, and other vehicles with unusual operating characteristics or designs.

Specially Constructed Vehicles

A Specially Constructed Vehicle is legally defined as “a vehicle which is built for private use, not for resale, and is not constructed by a licensed manufacturer or remanufacturer.” Specially Constructed Vehicles include:

  • Kit cars
  • Vehicles built from a combination of new and used parts
  • Dismantled vehicles that look completely different from the original

There are special laws and regulations associated with registering Specially Constructed Vehicles. In addition to the regular DMV registration process, these vehicles must be inspected by a Smog Check Referee prior to being registered and, if required, must pass a smog check.

Obtaining an SB100 Certificate

An SB100 certificate allows you to register your specially constructed vehicle as brand new (called a SPCN), but exempted as if it were a 1965 or older model. The DMV gives out 500 SB100 certificates a year on a first-come, first-serve basis. There are four steps to apply for an SB 100 certificate:

  1. Fill out the paperwork, including an “Application for Registration” and a “Statement of Facts” form, which are available at the DMV. Once complete, you will be assigned a SB 100 number.
  2. Set up an appointment at a California Highway Patrol office to obtain a VIN number. Bring all paperwork and receipts showing VIN numbers for your vehicle’s engine, transmission, and other components.
  3. Make an appointment with a Smog Check Referee to get an inspection.
  4. Bring all paperwork back to the DMV, where you will receive your plates. Be sure to keep copies of all paperwork that you receive during the registration process.

Engine changes and modified vehicles

If you changed your vehicle’s engine and it is now different than the engine originally installed in the vehicle, or if you modified your vehicle with aftermarket parts, you may be required to have your smog check performed by a Referee.


Find out more about engine changes on page 45 (Appendix D) of the Smog Check Reference Guide: BAR Engine Change Guidelines.