Grand Theft Auto 5 to disappear after being parked in a garage. The glitch can erase a car "if you drive another character's personal vehicle," and for now Rockstar suggests players avoid parking in a garage, driving a car found in a garage or driving a default vehicle, at least not "when playing as a character other than the one with your upgrades."
There's no fix for the bug now, but to receive automatic email notification when a patch comes through log into Rockstar's Support Site and subscribe to this page.
Grand Theft Auto 5 roped in more than $1 billion during its first three days at retail. Surely it'll post a fix for this car bug once it's done counting all of its cash.