I purchased this game today 20/01/18, under the impression that I was buying the U.S. ELECTION NIGHTMARE SPECIAL EDITION. After playing the game for a while, I found no indication that this was inclluded with the version I purchased. On the web page it shows quite clearly with U.S. ELECTION NIGHTMARE SPECIAL Edition.
Can someone please clarify?

The game page states that they are game modes, as follows, so I guess there must be some way to activate the modes:

Carmageddon: Max Damage for PC features these 3 additional game modes:
Trumped-Up where every pedestrian is respectfully replaced by the President of the United States.
Hillaryious in which you’ll meet nothing but duplicates of the defeated Democratic candidate.
Mass Debate which features a politically correct balance of both characters.
Animals remain in the mix too – suitably accessorised… You haven’t lived till you’ve knocked the wig off of a penguin!

I saw that post in Steam, but that's not possible in Galaxy.

I read the game manual and couldn't find any mention to the trump and hillary game modes, only the normal game modes that are available in career mode.

you should be able to start the game with the following command line switches:
-pedsubstitution trumped_up.txt
-pedsubstitution hillarious.txt
-pedsubstitution mass_debate.txt

These launch options were available in the Steam version but i haven't had a chance to grab the GoG version yet to see if there's a way of setting the launch options from Galaxy.

It works!
Open GOG Galaxy (be signed in) then choose Carmageddon>More>Settings.
Activate custom settings and just put one of the three lines from the post above in the row below the custom settings (including the dash).

-pedsubstitution trumped_up.txt

-pedsubstitution hillarious.txt

-pedsubstitution mass_debate.txt

Then start the game in GOG Galaxy and enjoy.

Thanks DevilboxGames

Hopefully this can also be done without using GOG Galaxy just by creating custom shortcuts each one with one of the three command line switches appended to the end. I might give it a try later.

Yup that will work.

Thank you very much kind sir, I needed this!

Yup, works without Galaxy. Just right click on your Max shortcut, click properties, add any line to the end of your Target line. Put a space after your Max_Damage.exe

As korell posted you could also make three custom shortcuts.

Yup. Works for me. Thanks very much for that :])))))

There is no need to do any editing configs etc that other people have replied just right click the game in your library list and go down to OTHER and there are all the U.S Election stuff ,hope this helps others that are not as "tech savvy" :)