I love this game, and the graphics are still great even after 5 years. The game "supports" widescreen resolutions, but when I use a 16:10 res like 1920x1200, the aspect ratio is not adjusted. Everything just looks stretched out and crushed. Not finding any option to change this, I've set it back to 1600x1200. I use the ATI control panel to maintain aspect ratio with GPU scaling, so I get the black borders on the sides, but at least it looks proper.
Anyone know of a way to fix this so that it looks correct in a widescreen res?

Checked the games folder for config files you might beable to tinker with?

I know it's an old topic but it's now possible to play FlatOut with a correct aspect ratio in 16:9 (e.g. 1920 × 1080) and also 16:10 (e.g. 1920 × 1200).

Just follow these steps:

1) Google for: "site:github.com flatout widescreen fix" (without quotation marks)
2) On the GitHub page, download the file flatout_widescreen_fix.zip (latest version is v1.4 at present)
3) Extract the three files inside the ZIP archive to the root folder of your FlatOut installation (in my case it's c:\Program Files (x86)\GOG.com\FlatOut\)
4) Make sure you've set the correct resolution in the FlatOut setup ("Setup FlatOut" in the Windows start menu)
5) Enjoy! :-)

Directlink to Flatout (2) widescreen fix:

FlatOut 1 WS fix
FlatOut 2 WS fix

Is there a way to fix this in the Linux package
or at least a way to change the resolution afterwards into a 4:3 one?

I tried already before reading this thread, but it didn't do anything.

I was talking about FlatOut1.
Since I didn't find any [Software\\Wine\\DllOverrides] in user.reg, I inserted it and "dinput8"="native,builtin" under it.
After starting the game the game and sound works but the screen is and stays completely black.

Didn't FlatOut 2 have proper widescreen support at a certain stage of versions anyway? My retail CD had normal widescreen.

The solution for FlatOut 1 should be the same, but I don't think you can just add [Software\\Wine\\DllOverrides], If you notice all the other sections in user.reg will have a number after them, copy the same number. Also the sections are in alphabetical order but I don't know if that matters.

It's really best to use winecfg, which someone can correct me if I'm wrong, but I think is now ./start.sh -c with the new update.

As for FlatOut 2, it has hacky support for widescreen built in, where everything is just stretched. The patch for it fixes the field of view and shrinks the hud elements back to their proper dimensions.

Edit: removed the quote of my earlier post.

There are several different large numbers after the entries. Copying one resulted in making the menu visible again minus the 3D area (car, langscape, etc...).

In Winecfg I found libs -> dll overrides and created a new one for dinput8.
First I tried "Native, Builtin", then "Builtin, Native", but neither changed anything or crated the entry in user.reg.

If neither affected your user.reg it seems like you were running winecfg on the wrong prefix. How were you running that command?

The option you want is "Native, Builtin" which will prefer the 'native' dll included in Windows (in this case the one from the wide screen patch), over the dll built into wine.

Also I assume you are running v. 1.4 of the widescreen patch. (Older versions included dsound.dll instead of dinput.dll).

Including any other console output could be useful. (Does the game run for you without the widescreen fix?)

I just used the prearranged tarball-package.
I also user the winecfg in there (FlatOut/wine_standalone/lib/wine/fakedlls/winecfg.exe)

How does it find the d8input.dll in "prefix -> drive_c -> GOG Games -> FlatOut" anyway (where I was supposed to put it)?

There was no version indicator in the package, but it had a different filesize than this one which seems to be 1.4:
https://github.com/ThirteenAG/FlatOut_widescreen_fix/releases/tag/v1.4

The game runs anyway, I just hadn't got changes or the 3d elements. Since I'm using Mint atm I don't know how to see the console output.