This is the coolest thing i've seen in a long time. I've been lurking on eab for a very long time but have never needed to join. But today I had to join eab just to let you know how awesome and cool you are djvernon!
Releasing the c++ source AND the 68k source is just too much, the most i ever disassembled in the old days was 250kb - but 450 kb of 68k source?!! that is real dedication.
I have written quite a few 3d graphics engines and would encourage you to try doing an OpenGL port, since you are not using multi-textures or pixel shaders etc there should be a 1:1 correspondence between most direct x features and OGL ones and it would be alot of fun to learn and the game would then work on a range of platforms.
I'd also encourage you to add multiplayer/network play. In the old days my friend would come over and we'd connect his ST to my amiga and play Stunt Car Racer multiplayer for hours instead of studying for school. I can imagine how much fun it would be to start up a Stunt Car session at work on the local LAN after a Friday afternoon pint and have 8-16 people all trying to get the fastest time and knock the others off the track!
Once again kudos to you, most people are pure talk when it comes to projects like this but very few will see it through to release, well done! :-)