Really good quality. Looks like something Carface will do.

@demosfen Ah so you mean livery. Well for that the car must be UV mapped and you should have some paint.net or photoshop skills for it.

Do you mean by colorable paint in Zmodeler or coloring car in game (tuning) ?

It's not recommanded to add Add-On cars to Map Editor as if you publish the map mod players will have trouble as they don't have that addon car mod installed. You can try to spawn vehicle entity by it's spawn name, if it will work.

Well the reason for the crash is your gameconfig.xml as it is only edited to keep Rockstar DLCs, and to fix that you need to download gameconfig.xml from website by FY70, and install it to the path it says, AFTER that you can install DLCs and everytime game is updated you need to wait for SHV and the gameconfig to get fixed. Unless you have pirated game, we'll not be bothered with helping you.

Honestly fairly not possible as if you know Manhunt 1 and Manhunt 2 (both games) maps are set in levels and they are not united. And by far for San Andreas, GTA UG converted half of the maps with little interiors and not that far good overall. A mod for GTA SA called OpenManhunt has converted all the maps in convertable formats with proper collisons (MH1 and MH2 data files are preety hard to collect) and OpenManhunt has no proper lightning that's sad. And the levels are not connected (unless it's the Wrong Side Of The Tracks level, with the train station) which can be duplicated to unite the towns but will need so much 3ds max modelling work. So unless they are not united they would be useless, plus MH1 and MH2 (i finished MH2 twice, it's player camera views are preety limited and not in 360 form, just a simple VC-like spin with no X axis. So by that if the Carcer City and Cottonmouth levels would need HUGE WORK to be properly looking. Maybe someday EncryptedReality will try to port it.

Attach the plate to the back door.

You are using a pirated version of ZMOD3 and it cannot identify the shaders (made in so newer ZModeler 3.2.1+ legit copies) and by that it can't find the new shader. You will have to click on the material, and toggle a new material (e.g interior2) and then assign the missing texture to it and then export the car (if you're surely done)

dolmat has one in work, so does sparkv but he "bought" the model and yet it has no interior while there's one in GTA IV, that can be unlocked for converting, it has a hq int. if anyone can help me on that i can convert it