A vehicle will self-destruct after a certain amount of time if abandoned some distance from its spawn point. This type of damage is important for game play, as it means that abandoned vehicles will eventually disappear and then get replaced. Unlike most other damage factors, these settings are found in the level's battle type ObjectSpawnTemplates.con file. Here is an example:
ObjectTemplate.TimeToLive 45 ObjectTemplate.Distance 40 ObjectTemplate.DamageWhenLost 10
These settings mean that if the vehicle is moved 40 meters or more away from its spawn point, it will have 45 seconds to live unattended. After this period, the vehicle will take 10 Hitpoints of damage each second.