I need some help. Do you guys know how vehicles work in Simpe?

I tried replacing a quad bike with a custom vehicle, but the results in-game didn't turn out so good. When the sims drives off, the custom vehicle keeps disappearing and reappearing, and it doesn't match up with the movement of the sim.

What else do I need to do?


Here is what I have been working on:
https://www.mediafire.com/file/bp85...st.package/file