HOW TO GET RARE car in online (any car)
1. Get into singleplayer and switch to Michael.
2. Go in front of his garage and sit in a random vehicle. (We'll use the adder here)
3. Open your phone and do a quick save to your USB Stick.
4. Unplug the USB and stick into your PC's usb slot.
5. Use Horizon to extract the save file from the stick.
6. Use the GTA V editor to edit your current vehicle. (Current vehicle editor)
7. Save the Content file.
8. Resign the whole thing in Horizon and put it on your flash drive, then in your console.
9. Load the save and back the car into your garage.
10. Join your friends invite only session.
11. Do the singleplayer in MP glitch until you spawn in michaels house. (IMPORTANT)
12. Unfreeze Michael using the Xbox store.
13. Go into his garage and your vehicle should be there.
14. Now get your friend to come to the garage, if he is there before it will NOT work.
15. Stand in front of the garage, open and close the gamestore, a dupe will now be standing outside the garage.
16. He will then glitch it into his garage.