All the vehicles, including my own, are a lower LOD.
I tend to play with traffic and peds off, but when I turn it on then for some reason all the cars have a lower level of detail, including my own. Only recently started experiencing this. Because of this, the cars look like they're from GTA IV, and have crappy interiors and whatnot. Some add-on cars look especially crappy due to their low polygon count on the LODs.