I played it for 2-3 hours, here is some feedback: the physics is almost perfect but the "stepping stones" seem harder than the original - you have to be more precise on the win32 version, however I last played stunt car racer perhaps 20 years ago and may have wrong memories!
One thing you could immediately do to improve playability is not restart the player in between the two "arms" of a ramp if they crash on a ramp/jump. similarly in the original if you crashed on a ramp/jump, you would always be restarted at a position that would give you sufficient "run up" to get over the ramp.
Next priority could be to get the "push up/forward to accelerate, firebutton for turbo" functionality working, because i think in the win32 version the only way to go forward is to burn turbo?
Thank you djvernon for many hours of fun! :-D