This is tested on NVSurround, reports from Eyefinity show the HUD is NOT centered fullscreen but the AR is correct.
I don't think that's true;
RED-FROG's screenshots suggest the exact same problem cripples Eyefinity, too.
Anyway, here's how the demo compares to the retail version (still v1.0 ATTOW)...
5760x1080 fullscreen, Auto AR, top=demo, bottom=retail
Chase cam
Bonnet cam
It looks like the retail game uses a combination of zoom-in and dolly-out in fullscreen Surround. Although the retail chase cam shot may look "okay" at first glance, the in-game feel is atrocious: the perspective is wrong, and feels a bit like playing a Vert- FPS with a properly centered, non-cut-off weapon model. It makes Surround look weirder, not wider than widescreen.
Interestingly, all the menus, cut-scenes, loading screens... have a flawless, strictly Hor+ FOV in both the demo and retail game.
Race menu
Cut-scene
So the FOV has been tampered with (and ruined) only for proper gameplay, in fullscreen mode. If devs really prefer this sort of botch job to the possibility of some clipping here and there, we're doomed.