After a fair bit of experimentation, I've managed to compile my 6-page Need for Speed: Most Wanted Tweak Guide for the demo, and for when the game is released in stores. It's a fairly brief affair, mainly because much the same as previous NFS games, there is little room for any advanced tweaking. The game has been designed for consoles, and as such there are no major .ini/.cfg files which can be played around with. So instead the guide focuses on giving you the rundown on how the various in-game settings affect image quality and performance through a series of screenshot comparisons and performance discussions.
It rounds these out with some troubleshooting tips and general performance optimization information which should help you squeeze the most out of the game on your machine. Give it a run-through and you'll see what I mean.. Head over to Tweak Guides to read more.