I’ve blogged before about the kind of audiobook that makes good road-trip listening: as I put it at the time, “a book that isn’t so complex you’ll lose track of everything else you’re doing, but with enough stuff going on that you’ll stay alert and not succumb to highway hypnosis.”
Our most recent road book discovery has been the Victorian mystery novels of Wilkie Collins. Not only are they full of interesting characters and incidents, they’re also long and full of enough plotty goodness to beguile a couple of eight or ten hour round trip journeys each. We started out with The Moonstone, which involves (among other things) a mysterious gem stone stolen from the eye of an idol, and have moved on to The Woman in White (which after only about a dozen chapters – out of sixty-two – is already promising us a Bad Baronet.) The former is available for free from Librivox, and in several for-pay versions; the latter is available for free from Lit2Go.
An unexpected (by me, anyhow) bonus: For a Victorian male novelist, Collins does some excellent female characters. He’s definitely better at them than Dickens, whose female characters usually make me want to slap them silly.
Dr. Doyle's Blog 
“When I’m a bad bart I will tell taradiddles…!”