Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Smart Tuning System Free.
Smart Tuning System v1.0
Smart Tuning System (STS) represents a complete innovation for vehicles tuning game. It is the best way to implement vehicle tuning system in your game. It is a complete, powerful and optimized script package, designed to fit every developer requirement and to be easy to use! You can also use some or all system’s feature and integrate them into your game without problems.
STS package contains:
– Complete vehicles tuning system;
– Advanced Decals System;
– Load/Save solution for vehicles game;
– Random managed tuning for AI vehicles;
– Cheat system;
– Options system;
– Some minor scripts plus every asset showed in pictures or videos.