TDU2 seems harder to mod and hack than TDU1.
Specially because Eden Games (Actually Atari is to Blame) has encrypted all base files for modding.
And we need to look a bit around, but the modding community for TDU1 and 2 is not the same anymore, since many mods has been stolen, great mod creators retired, among other things..
And TDU1 and 2 DOES NOT have a modding community like GTA, post-2002 NFS and BeamNG has, which has script mods, vehicle mods, effects, ect almost every week.
TDU2 is cool, has a fancier world, has a better SP campaign (PS2/PSP TDU1 has the best SP Campaign in a racing game ever IMHO), but TDU1 is more customizable and less painful to edit assets, make mods, ect...
Also, I DOUBT someone has the guts to reverse engineer the code and stuff, specially because if they do, MOST LIKELY they'll be lawsuited by BOTH Atari (since they still own the assets and resources for TDU1 and 2) and BigBen Games (since they CURRENTLY own the IP).
And honestly, i wouldn't put hopes with more cars since no one posted a tutorial for add car slots to TDU2, and besides that, the dealership and customization system is much more different than in TDU1.
TDU2 has an multiplayer mode, but Atari has shut down.