Avatars for plugin objects

hi, I have a "Cars" plugin that allows users to add car objects to their profile. i plan on allowing them to write blogs about, upload pics for their cars, etc. Also plan on showing cars in a gallery, etc. 

I'd like for each car object to have an avatar/icon that can be displayed in various sizes much like the profile icon. What's the best approach to do this? I've experimented and added code to the Car object where I (currently manually) enter the guid of a pic uploaded using the File plugin. This is cool in that I can show the pic in various views in different sizes--however I'd prefer to have a separate "copy" of the avatar linked to the Car object so that it's independent of the file uploaded in the File plugin. Does anyone have experience with avatars outside of the Profile plugin? How could I save the avatar to a Car object? Thanks!