Big Bucks! 25
Earn those big bucks.
Earn $999,999. NOT CUMULATIVE. Meaning you must have a balance of $999,999 or €666,666 (Thanks to Alexgaara for pointing this out) for this to unlock. It wont add up and unlock if you keep spending. Thanks to blitz7287.
This is seriously easy and you'll get it whilst you're still at rookie level. Just do every event you can on serious rating, this setting is still incredibly easy and yields a good amount of cash. Do all of the events you can that don't require you to buy a car and ONLY spend money on cars when you're prompted to. Should unlock at around rank 9/10 and once you've got it you never have to worry about spending again!