I'm not aware of any study, but having listened to over a hundred audiobooks on the last few years, I would like to share my experience while listing to non-fiction.

My experience is that retention depends mainly on two factors: the amount of attention and quality of the reader. I prefer when the author is the one reading because many of them add comments and a special "energy" to the book.

I find the "car mode" on Audible very convenient to add bookmarks without disruption while I'm driving and I use at the gym as well.

Some books that I want to reference later I buy a paper-copy and mark with a highlighter on the same places I bookmarked on the Audible App.

While listening, the faster I play, the more attention I pay. I start at 2X and if I'm listening to the audiobook a second time, I can go up to 3X. 1X and 1.5X are for engaging parts or when I can't understand what is being said.

One thing I don't do is: listen while not able to pay attention. While dring it can be while going through a toll or navigating through unfamiliar streets.

With all said, the feature that I think is the most useful for retention is the Pause button. This way I can reflect on what I just heard and save the information on my brain's long-term storage.