California Code, Vehicle Code - VEH § 5051

(a) “Collector” is the owner of one or more vehicles described in Section 5004 or of one or more special interest vehicles, as defined in this article, who collects, purchases, acquires, trades, or disposes of the vehicle, or parts thereof, for his or her own use, in order to preserve, restore, and maintain the vehicle for hobby or historical purposes.

(b) “Special interest vehicle” is a vehicle of an age that is unaltered from the manufacturer's original specifications and, because of its significance, including, but not limited to, an out-of-production vehicle or a model of less than 2,000 sold in California in a model-year, is collected, preserved, restored, or maintained by a hobbyist as a leisure pursuit.

(c) “Parts car” is a motor vehicle that is owned by a collector to furnish parts for restoration or maintenance of a special interest vehicle or a vehicle described in Section 5004, thus enabling a collector to preserve, restore, and maintain a special interest vehicle or a vehicle described in Section 5004.

(d) “Street rod vehicle” is a motor vehicle, other than a motorcycle, manufactured in, or prior to, 1948 that is individually modified in its body style or design, including through the use of nonoriginal or reproduction components, and may include additional modifications to other components, including, but not limited to, the engine, drivetrain, suspension, and brakes in a manner that does not adversely affect its safe performance as a motor vehicle or render it unlawful for highway use.