https://bugs.winehq.org/show_bug.cgi?id=46666
--- Comment #10 from Alex Henrie alexhenrie24@gmail.com --- So, it wasn't documented anywhere obvious, but Wine does not support 256 color mode without a window manager that supports color palettes. I have edited the instructions at https://wiki.winehq.org/256_Color_Mode to say to start Openbox in Xephyr before starting your application in Xephyr.
In my testing, Openbox greatly improved the colors in Al Unser, although there are still a lot of graphical glitches and I had to switch the window between "restored" and "maximized" a couple of times to get it to display anything at all. I hope that helps!