The amount of data per item can degrade over time. During a wreck you have full details. Once the clean up crew leaves, you just need to record that 'NPC is h

The amount of data per item can degrade over time. During a wreck you have full details. Once the clean up crew leaves, you just need to record that 'NPC is hosptalized' and 'blue car (model 123) has 35% damage'. Later on, NPC goes by a mechanics, you can query the list of damaged vehicles, maybe load one being worked on in the garage, and if so remove it from the list. After a few hours items roll off the list (representing them being taken care of outside of the NPCs knowledge). The real trick is getting it to happen enough to be noticed but not enough to be seriously investigated so you can increase immersion without breaking it. I've done a variant of this in a D&D campaign to simulate the world around the PCs, increasing detail only as it became more relevant to the PCs. Not something I recommend doing by hand w/ dice rolls.