Nice industrial-clean effect. I like them too!
One question (before I steal your idea
): How do the rings slide along the car, compared to how they slide along a round rod? Do they bind? Can you just "swoosh" them open and closed like on a round rod? Or do you have to help them?
Also, I've never thought of attaching the rings in two places. I've done curtains like yours but only with the bottom stitching on the ring. I guess I have the same question as above: Do they glide right along?
(In case you can't tell, I have an aversion to curtains that need "help" to open and close. I guess I'm super lazy but that usually means I just leave them closed