Update: thanks to a comment by Bill McCoskey, it turns out this wood kit was supplied by Chevrolet as an option on 1948 Chevrolets. Full details at the end of the post:
No, it’s not original, but we can pretend, eh? My friend Paul B. shot this presumably near the water in San Francisco, given the fog. I have a major soft spot for GM fastbacks of the era, and this Chevy Fleetline is a very tasty example. I think I’d do without the wood applique, but it does add a bit of contrast to the black paint, and it is rather period-correct, unlike some others that I’ve seen.
A bit of zooming in suggests that the wood “framing” is the real thing, and the the larger panels inside it are probably a faux paint finish on the original body. Looks quite well done.