Highly modified and/or Restored vehicles with uprated, non-period correct engine swaps, or engines from outside the original manufacturer, and/or vehicles with significant body customizations or conversions. Generally, Custom vehicles cannot be easily returned to their original factory specifications.

Vehicles with a period-correct engine and body, with multiple removable modifications, or a few significant modifications such as increased displacement, added performance equipment (turbo, supercharger, headers), transmission swaps, bumpers, or body wraps. Modified vehicles can generally be returned to original factory specifications.