From Multi Theft Auto: Wiki

On April 06 2010 - 7:22 GMT Cezar said:
How does this work? Does it save information on the client's computer? Isn't that prone to hacking?

Accounts are completely serverside so their data is probably serverside, too. But even if this data would be clientside MTA does save all data in a save xml format, which cannot be destroyed due to escaping and stuff, so no need to worry.
NeonBlack 18:36, 6 April 2010 (UTC)

On April 06 2010 - 7:47 GMT Cezar said:
Thank you for the quick reply :). I just want to be sure that the user has no way of modifying the data.