Apparently with some patch they added 5 different difficulties. GOG version of course already includes this patch.
But I have hard time finding which of these 5 (very easy, easy, normal, hard, extreme) equals the only difficulty in original game.
I would assume it's either normal or hard as they probably added at least one harder difficulty.
Normal was not that hard, you can make it in 5 tries. Same was with original game which I played in beginning of 2003, it was not that difficult to complete it.

Here it doesn't say anything:
[url=https://mafiagame.fandom.com/wiki/Fairplay_(Mafia]https://mafiagame.fandom.com/wiki/Fairplay_(Mafia[/url])

In any way I will also install the original 3 CD version and make my own conclusions.

After driving for more than 2 hours, I think Normal is equal to OG.
Extreme is way harder, first one is just gone.
On Hard at first attempt white one was right behind me, but on second attempt, they were all at least 20s behind me, 2nd and 3rd probably spun out at least one time. On third attempt white one overtook me right before the finish.
Now this one is a challenge and certainly harder than OG.