That's great, I was thinking you'd have to turn the knob too fast to be usable. Have you tried adjusting the mame dial sensitivity in the other games.
The driving controller becomes a mouse axis; is that correct?
The controller reads as joystick y+ and y- in the AdvanceMame 1.4 input settings (other emulators like mame2010 don't even recognize it). It's a bit twitchy, but more natural for driving than using the joystick or L/R buttons. Interestingly, I'm not able to enter high score initials, as the letters cycle continuously as though the dial is being quickly turned.
No amount of adjusting for sensitivity will work for Night Driver or Speed Freak. The car just quickly veers off the road. Seems odd, since I'm using the same emulator, but I've seen that same behavior when trying to configure other racing games.