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 that are original or close to original factory specifications, irrespective of condition. May include vehicles that have minor, removable modifications such as aftermarket wheels, exhaust, or accessories such as cargo/roof rack, stereos, etc.

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.