Of course you can just use sensors in your project, and resell it as such. No problem there.
But:
- 3D printed case is OK for prototyping. Far too expensive for any commercial product.
- you'll have to make your own PCB. Clamping stuff on an Arduino is fine for prototyping, not for any commercial product. It's too expensive to make, too bulky, too unreliable.
- a joystick is not much better than touch screen for control during driving. The driver should not be controlling anything, but keeping his eyes on the road or just a quick glance on the display (I hope you know why they still use rather large analog dials in cars, rather than displaying the number on an LCD).