Certainly hope so, in fact I would like to do a lot more with terrain in the future and as we build up our 3D vehicle 'database' as such that should indeed be possible including many more trees, flavour objects, etc.
One tricky part about cars as a flavour object is that to be realistic they need to be able to burn and they are large yet light enough to need to be movable or destroy-able by vehicles, which will likely require some further work on Charles end. In theory we could make a simple one that would somewhat work under the current flavour object system, but Id prefer to wait until we are able to have them go from a regular car, to a destroyed car to a burning car as they should.
Something I am working on for the nearer future are modular build roofs with proper 3D models for damage showing beams, etc. For such a small change as such (well not on my end, I think it requires around a couple of dozen models hehe), the overall affect of them should be very pleasing I think
Dan