California Code, Vehicle Code - VEH § 580

A “specially constructed vehicle” is a vehicle which is built for private use, not for resale, and is not constructed by a licensed manufacturer or remanufacturer.  A specially constructed vehicle may be built from (1) a kit;  (2) new or used, or a combination of new and used, parts;  or (3) a vehicle reported for dismantling, as required by Section 5500 or 11520, which, when reconstructed, does not resemble the original make of the vehicle dismantled.  A specially constructed vehicle is not a vehicle which has been repaired or restored to its original design by replacing parts.