Tutorial:
1. Go to invite only session and drive your car worth over 50k and park it right outside LSC (Make sure your spawn location is on "Last location")

2.Leave GTA Online and head into Story Mode

3. When story mode loads up, hit the guide button then sign out

4. It should restart the story mode and it will load up the cutscene from the beginning of
the game

5. When the cutscene comes sign in to your account again

6. Then hit pause go to Online and start an invite only session

7. You should spawn in the car u want to sell, drive it closer to LSC and park it outside

8. Then find a random car and crash it once then drive it inside LSC, Dont REPAIR THE CAR.

9. Hover over sell and click sell once BUT dont sell it.

10. Pause the game go to Xbox Game Store fast then exit Xbox Game Store

11. You should then spawn in your car that u bought for over 50k

12. Drive it into LSC then click sell twice when it says sold click start then click online and swap characters, pick your character

13. Good work u done the glitch now repeat step 12 as many times as u want

This could take u a couple of tries, but it works. I managed to do it after two or three tries. If you have any problems please dont hesitate to ask. Remember im here to help