Is there any way to add glossiness to my plane track in the compositor?
Can you be more specific?
No, not in the compositor. To get any kind of 3d shader effect, you would have to go into 3d.
You could always cheat it by using rotoscoping to hand-draw the glossy reflection you want to see.
What you can do in the compositor, if you rendered the material into MultLayer OpenEXR files with all the necessary channels selected, is to extract (say …) just the specularity, and maybe only what’s falling on a particular object(-id).
You can also create “pristine” special-purpose renders that are specifically intended to produce only a certain channel or type of information, specifically for compositing-input purposes. (e.g. “a shiny track in empty space.”) Analogous to the sort of things that are produced for assembling a musical recording: a single instrument or effect in an isolated room, which is then “mixed-down.”
You can be very, very precise in how you “mix-down” a CG image “in post,” but you have to plan ahead to have the “pristine, isolated” channels of input data that you will require. It’s well worth doing, because it can dramatically shorten total render time, but it demands a lot of careful planning.
If you’ll describe here more-completely … where you’re coming from, what you want, maybe an example or three … then you’ll get a more specific and useful response.