The names of the vehicles are stored in the file "name.txt" within the corresponding vehicle's sub-directory. What my mod does is adding the IRL name of the respective vehicle in parentheses. For example:

Royale Bianco

becomes

Royale Bianco (Fiat Punto Mk.3)

Similar mods exist (e.g. this one), but their files were hosted on filesharing sites and are no longer downloadable.

My mod is available in a Github repository, so it will hopefully be available for longer with the added bonus of Github's transparency (the content of every single .TXT file can be viewed before you download it):
https://github.com/VassilevB/cms2018irlcarnames

Download is easy:

Install is also easy: extract and overwrite your default CMS2018 game directory and you're done.

I hope you enjoy.