Does The Simpsons: Hit & Run have the HUD stretched on non 4:3 resolutions?
By default, the only resolutions available on The Simpsons: Hit & Run are 640x480, 800x600, 1024x768, 1152x864, 1280x1024 and 1600x1200, and all of them are 4:3. To use resolutions that are not 4:3, you need to use a 3rd party tool called Lucas' Simpsons Hit & Run Mod Launcher.
To use it, you just open "Lucas Simpsons Hit & Run Mod Launcher.exe". You can choose any non-default resolution on the DropDown at the bottom right side of the window, but to fix the aspect ratio you need to enable the setting tweak called "Aspect Ratio Support".
To enable "Aspect Ratio Support", you need to go into the Settings tab and enable the patch on the list. By default, the aspect ratio is detected automatically, but you can force any aspect ratio by selecting the patch, clicking "Mod Settings...", disabling "Automatic Aspect Ratio" and selecting an aspect ratio on the list.
After that, you can just press "Launch" to open the game with those settings and patches.
Here is a little comparison of the game on 1366x768 with and without the "Aspect Ratio Support" patch.