Easy money:
To earn extra money, repeat any challenge that you have already won.
Recommended car:
Choose the Audi TT 3.2 Quattro when you can get the following cars; Mustang GT, Mazda RX-8, Audi TT 3.2 Quattro, and Subaru Imoreza WRX STI.
Legendary chassis hint:
Fully kit out the Volkswagen Golf GTI, then race the Blacklist driver on Chapter 1 around five or more times to unlock the Legendary chassis.