Yes, and those projected reflections would be mapped absolutely correctly, given that you would model holdout objects in the same/similar distance actual real scene elements were captured on the backplate when shot. I do that all the time when doing VFX integration into footage. If you put plane very far away and make it small enough to cover just window, I doubt you will get any visible reflections projected on your car.
Actually, I will often take extra time to blockout some elements on the backplate to make scene even more realistic, such as for example street lamp close to the car, so that it gets reflected in the car hood/windshield, etc...
Everyone keeps talking about solution, yet no one knows what the solution is. No render engine has any advanced AI, that can differ which mesh is modeled in a way, in which it does not refract any environment outside of the camera's field of view, and which meshes with refractive materials bend the rays, and need to refract the environment.
Owlempires has stumbled upon this problem in one of the previous posts, where enabling refraction environment messed up his other glass materials. This is what I mean. If we had yet another override called "backplate map", what would that override do? In which ways would it be different to the existing refraction environment? I am sincerely asking here, without any angry tone.
You have simple solution of putting a small plane behind it, which never failed me in my life, and I did a lot of cars integration, and then you also have Refract BG Override slot at the bottom of each CoronaMTL, into which you can instance your screen mapped backplate, so you get refraction override only on materials selected by you.
I can't possibly imagine scenario where both these mechanisms would fail.