pushing the gas pedal 50 percent to stay still and letting your foot off to go backwards.
Does that happen when you set the gas pedal axis to accelerate? It sounds like the pedals are mapped from -1 to 1 instead of 0 to 1, which could be an issue. Can the drivers change that mapping?
There's also no Z axis input in C:R that I can tell. By the sounds of it what we need to fix this is software which maps the accelerator pedal to the 0 to 1 values of the xbox trigger axis, and the brake pedal to the -1 to 0 values. I would guess the best way to do it would be to that would be to write a piece of software which intercepts the xinput DLL's XInputGetState function function, polls the wheel's state using DirectInput and creates the XINPUT_STATE/XINPUT_GAMEPAD structures using the corresponding values pulled from the wheel and map the values accordingly. And a method of configuring that easily. What could be easier? I'm going to have a poke around in x360ce's source code to see how it works and see if I can figure out a method of hooking xinput myself and see if how plausible it is to create such a tool.