The gameplay time doesn't count if you have 20 million from 20 car sells which you would normally only reach by selling thousands of cars. What you can do is sell them for a lower price each, I don't believe R* will track down each detail from each transaction on thousands of players that used this method.
Rock* keep the money you earned in career stats, even if you delete your character the money still there.
Btw, anyone know how to use CE to change my k/d in online stat.
Is this still working and safe for RP ?