What folks really want to do in GTA Online — and most heavily populated multiplayer games, really — is stand out. Y'know, show off some skills or styles that not just everybody can flaunt. So, this floating car glitch will probably interest many people. You'll need a friend to pull it off though.
This glitch seems to only popping up in the new-gen versions of GTA V and, based on videos explaining how to do it, looks to be pretty easy to replicate. Two variants have shown up. One — shown in a YouTube video by TwoDynamic — requires players to damage a car and take it into to get repaired at Los Santos Customs with a friend in passenger seat. The other only seems to require players to install a neon undercarriage customisation, as seen in FCGlitching's clip below.
The wheels don't move on the floating cars and neither variant seems to break the driving physics. This seems like the kind of bug that will get patched out really quickly so head over to Los Santos Customs ASAP to try this out for yourself.