interior chassis is invisible idk how fix it 
but but when I'm in the car the problem does not appear, but when i leave in car it appear 
its San Andreas bug, at night time when car lights are on, (on that car) everything from one side turns invisible, try at day time and you see it without this bug
1. Select all the body polygons (vehiclegrunge256)
2. Modify>Submesh>Detach with "Keep original" "New Object"
3. On new object do Modify>Flip
4. Attach new object to original chassis.
5. Enjoy!
this will fix it, but then there will be more polygons and on low PC's its can make lags ingame