Update 4/11/23
Door sills has been modeled:

I decided to make the engine and other parts (bumpers, bonnet, spoiler, etc) as tuning options.
Sneak peek at engine choices:

Update 4/9/23 - Initial release

Update 4/10/23 - I found a suitable engine and trunk bay model. How about it?

First in game test, there's still a lot of work to do:

Hello, here's my first attempt on converting a vehicle to GTA V.
Project is around 20%, I've just finished texturing the exterior.
Let me know if you have any comments or suggestions.

My game crashed after installing any vegetation mods (e.g. GTAV Remastered, Forests of SA, Lively World Expansion, etc), but installing other mods like vehicles, clothing, MLOs, peds etc works fine - I can install 100 or more of them and everything works, but not a single vegetation mod. I'm on vanilla game version 2802 with custom gameconfig from F7YO, heap adjuster, packfile limit adjuster and resource adjuster installed. Any solution for this?