Is there a way to sort audio by file name in the music app on iOS 5? I got an MP3 audiobook download for Christmas.

The downloaded and unzipped files are named in this manner:


01 Prologue.mp3
02 Chapter 1 - Don't start yappin.mp3  
03 Chapter 2 - Stack  Exchangin your way to success.mp3
04 Chapter 3 - Don't eat that Unicorn meat and three other warnings.mp3
05 Epilogue.mp3


After syncing them to my iPhone and opening the music app I saw that they are displayed in alphabetical order by title:


Don't eat that Unicorn meat and three other warnings. 
Don't start yappin'! 
Epilogue
Stack  Exchangin' your way to success.
Prologue


Listening in the order they're presented in while I'm driving is bizarre.
Is there a way to sort audio by file name in the music app on iOS 5?
Have you tried setting the track number in iTunes and then syncing again?