Not as good. Mouse wheels have a 'click' when you rotate them. It's part of their 'feel'. It's really just a spring clicking into slots on the inside of the wheel, but it's an iconic part of the interface.
Sure, you could just use an encoder wheel... or a pot... or a button. but that wouldn't deliver the user interface experience of a mouse wheel.
In the context of a car's user interface, where you just want to reach over there and click it while barely looking...a mouse wheel click would be damn cool.
You could probably find rotary encoders for sale that have the click built into them, no?
Although the mouse idea may be the cheapest/easiest way to go about it. The encoder might just look more awesome.