I know you asked for Bose, but as I was bored I had to do something...
Just a preview, if you like it I can do the size you want and the XRT aswell.
(Don't blame me for the reflections, blame LFS for low-poly cars)
That's like saying F1 sucks big time - because you can't go rallying in one. Sure there's limitations, but if you want to become the artist, then it's your job to present the render in a workable way.
Pro photographers do this and they don't have to worry about lowres cars or whatnot. What they do is to plan how they want their light and reflections on the subject as well as pick the right angles and so on. Don't just do a quick job, hit render and expect good results. The renders may not be good even with a gazillion poly model, because there's much more to visuals than polycount.
Then say it was done in a rush, and don't blame LFS for it - we all know how the models are. I've done tons of renders and none of my reflections look that bad. Yours however look like the car had 3/4 of the polys reduced.
You need to pay attention to lighting and how you add the reflector - do it enough times and you'll be able to come up with better renders in same or even less time depending on final overall quality. But in this case. Same time or faster, for sure.