The TVTropes Trope Finder is where you can come to ask questions like "Do we have this one?" and "What's the trope about...?" Trying to rediscover a long lost show or other medium but need a little help? Head to Media Finder and try your luck there. Want to propose a new trope? You should be over at You Know, That Thing Where.
If its a sort of "bust into the jewelry store and take everything because there's no rules anymore" sort of thing, part of Apocalypse Anarchy.
If it's more a "As the last survivor in town, I have my pick of any of the abandoned cars. I chose that red one over there with the racing slicks and gull wing doors." you've got the overlap of Disaster Scavengers and Cozy Catastrophe.
Cozy Catastrophe's the one I want, thanks!
Is there a trope for characters taking advantage of societal breakdown to use expensive cars and other luxury items? Like if 99% of the world's population is gone, there are lots of ferrarris to go around?