Over the past two days I have (with Jinx and Johnny's help) brought motorcycles into line with cars in terms of having parts. This means:
Bikes can be hotwired and stolen.
Bikes can crash and become undrivable and unstartable.
Bikes can be customized (different engine, tires, etc).
Bikes take damage when crashed.
Bikes no longer become wrecks, they simple stop working as their parts are damaged.