These are perfect. It's so sad the custom license makes them not free culture. You effectively made them only suitable for personal and commercial use, as it would taint any free work that incorporates them.
It was never my intention to make them unfriendly for open source: the "as-is or minor modifications" part was just meant to stop people from reselling or redistributing the cars basically unchanged. I want to allow redistribution as long as they're properly integrated into a bigger project.
I'll update the license in the next update (coming very soon) to make it clearer and more open-source friendly
Awesome! And understood.
Any of the standard Creative Commons licenses without NC or ND flag would make them suitable for a project like OG Tatt: That is CC0, CC-BY or CC-BY-SA. We'd gladly attribute your work, but since your current license says no attribution is required, CC0 (more of a public domain waiver rather than a license) would probably best fit your intentions.