Amazon has a new free Whispersync deal for a free e-book and the audiobook companion (They normally update the free Whispersync deal every couple of months).
The audiobook is about 6 hours long - great for a long drive with the family.
If you're not familiar with the book, have a read through the review:
http://www.goodreads.com/book/show/295.Treasure_Island
To get it for free go to the link above and tick "Add Audible narration to your purchase for just $0.00" before you click buy
Then go to the Audible book here
You can login with your amazon e-mail & password. It should already be in your library or otherwise you can download it for free.
If you haven't used Audible before, you can get free 2 audiobooks by joining here. Don't forget to cancel after a month if you're not planning to be a member.
My recommendation for your 2 free audiobooks are Ready Player One and The Martian.
Cheers! :)
I can vouch for the Martian being a fantastic book. In the process of listening to it now and it is an absolutely great read!
I know this is not really related to the main reason of this post, but wanted to support the OP's choice.