Currently there's only space for one vehicle in the avatar. There's a few members here with two (or more). For an example, someone might be displaying a second gen Prius in their avatar, but they also have and are asking a question about a third gen Prius. They're posting in the appropriate 3rd gen forum, but it's still confusing sometimes. If there's a website redesign down the road: allow additional vehicles to display in avatar, as needed?
Thus far, the alternative has been to put your vehicle in the signature (and your primary vehicle in the avatar). I suppose it's possible to have multiple vehicles in the avatar but it can get messy. Let's see what @Danny says.
Some changes have been made behind the scenes. For example: the upload a file or picture button now works properly on a phone (it did work before, but you had to touch the text above the button), and it's possible now to upload multiple pictures/files in one operation. The first post edit screen on a phone is still problematic, with a pop-up that obscures text. Work-arounds are to either go to the advance editor, or (as you've mentioned) rotate your phone horizontal, then back to vertical. The latter action uses throws your location on the page off though, it takes some scrolling to find the edit window again. Bottom line with all that: maybe just ditch the quick edit, have only the advanced editor? I never did understand the point of quick edit; maybe it's just less data transfer, good for the site operation somehow?? All-in-all, comparing to other similar sites, Priuschat is very easy and intuitive, full featured. Alerts are the bees-knees, for example.