I personally don't like the aesthetics of the car base, so I'm wondering about how to use the wheels without the car base. The axle has the same dimensions of a bar, so it can be used with clip plates or minifig hands:
...but that will obviously have a lot of friction.
What building techniques and parts can be used to attach the roller coaster wheels (or, for that matter, any other bar part) to other parts with low enough friction?
I'm looking for techniques for play (i.e. the vehicle should move along tracks and hold together when shaken), not for display (which can be achieved by high-friction clips).