Okay, it took longer than a night but

...
Somthing is weird is going on with the driver & mame core. Digital devices (keyboard, 8-way sticks) work great (well, as well as a digital input can do at faking an analog input). Absolute analog devices (POT steering wheel, analog joystick, ect) usually work fine turning right, and sometimes work turning left. Relative analog (mice, spinners, trackballs) can only turn right. Other games that originally had absolute analog inputs, such as SpyHunter, play okay with all three types.
I have a couple guesses what's going on, but with the core input changes Coming Soon, probably not worth working on it. My top guess ATM: the minimum is set to 0xff7f & the maximum to 0x80. The decimal, these should correspond to -129 minimum and 128 maximum (in signed 16 bit), but 0xff7f could be seen as 65407 in unsigned 16 bit, or any 17+ bit. I think mame is thinking the min/max is -65407/128 since 65407 > 128.
A short time hack is to edit the topspeed.c driver and set the min,max to
0x81,0x80; it seems to work on my computer.
Or you can go back and use an old version of mame (0.112u2 works, 0.113 doesn't).