Conservation and restoration of vehicles  Vehicle restoration is the process of restoring a vehicle back to its original working condition. Whether the car is partially scrapped or completely totaled. Automotive restoration can be applied to many different eras of the automobile. Heritage railways and railway museums aim to restore and operate restored trains. Bus preservation groups aim to purchase buses of various eras to restore them to their original operating condition. Trains and buses are often restored to the original authentic livery of their original owner. Restoration of a vehicle refers to the process of restoring a vehicle to its original condition. Neither updating nor modifying are considered part of the restoration process. A restored car is one that has had all of its systems and/or parts restored to original condition. Selectively restoring parts or systems is referred to as refurbishing. It does not qualify as restoration. Rebuilding an engine may restore that engine, but it does not restore the car, or entitle the car to be called a restoration. A car that has had its bodywork restored to as new condition but has undergone some modifications elsewhere is either a modified car or a resto-mod car, neither being completely restored nor completely modified. If a car has had an engine swap for other than the original model, that car has not  been restored. Although most of the parts are original, it qualifies as modified rather than restored. There are many aspects to the process of vehicle restoration. The goal is to return the vehicle to its 'original' state. To accomplish this, a vehicle must often undergo many structural and aesthetic changes. The first project is disassembly. The car is taken apart and the chassis is inspected. The chassis must be in order as it is the structural foundation of the vehicle. The next tasks are typically the vehicle's engine and mechanisms. The restorer will mechanically bring the vehicle into working order before aesthetically restoring the interior and exterior of the vehicle. Once the vehicle is mechanically functional the body work is then done to the car. Once the exterior restoration is completed, the last task is the interior finish. The restoration of the car is complete when the interior restoration is completed. Interior restoration is the process of returning the inside of the vehicle to its original factory state. Often a vehicle’s interior must be need to be completely stripped out before restoration can occur. This is because deterioration over time that can leave materials like wood, cloth or leather in unusable condition. Also abandoned vehicles have the potential to contain biohazardous material within the cabin caused by decay and habitation by animals.