You may want to try a newer audio production by a very experienced and skilled narrator. As someone who has listened to over 1000 audiobooks, I can tell you that narrator/recording quality is just as variable as writing quality. When listening to an audiobook, not only does the writing (story, prose, etc...) have to hold your interest, but the narrator has to also pull their weight. Project Hail Mary is a recent release that has widespread appeal with a very experienced and talented narrator.

Also, you need to perhaps manage your expectations with respect to "remembering the contents of a book." That's not how memory works. You can't expect a single exposure (video, audio, or print text) to translate into defacto-knowledge that you can call upon days, weeks, or months later. Memorizable facts require spaced repetition, but even then, there's a decay in memory after repeated exposure to the information ceases.

As far as listening while you drive vs. listening while you work out, cognitive science doesn't support the active processing of auditory inputs while you are engaged in exercise. You might be expecting too much of yourself. Driving, on the other hand, particularly highway cruising and highway road tripping (not actively navigating or dense urban traffic), is a fairly automatic "background" activity cognitively speaking, so it makes sense that focusing on audiobooks is less arduous under these circumstances.

So, to summarize: there are a lot of factors that go into audiobook enjoyment. If you are still interested, I hope these talking points are helpful.