Pretty straightforward - when cruising in your '54 chevy you can gain additional adventure with a shifter knob that tells you what to do.
The exterior is a traditional 8 ball with a glass window on the top.
The inside is filled with liquid and a sixteen-sided dice with a variety of instructions
such as:
Shift up
Shift down
Bit faster
Cruise
Way faster
No
Yes
Next Left
Next Right
Honk Horn
Brake Check!
Get Romantic
Radio down!
Flash Lights
Radio up!
The physics will generally dictate less choices when things are slow, more choices when things are fast, etc.