Ways to have fusion parts
First, win some bronze keys in live racing. Second, accumulate the free bronze crate Donna supplys you every four hours. Next, have a part from winning a Daily Battle. Also, race every cup & trial race you may to win fusion parts &/or keys. Lastly, buy cars as well as strip them for fusion parts (for example, you may buy more t1 Fiesta STs to strip to have fusion parts for your t3 Mustangs or buy more t2 m235i to strip for your t3 BMW M4s). You will not have Mustang or M4 stage 6 fusion parts together with this way, but rather common, rare, as well as epic parts which are usable on any Ford or BMW cars in the game (Ford for Ford as well as BMW for BMW). To have stage 6 parts for the Mustang or M4, you would have to strip Mustangs as well as M4s.
If you truly want gold as well as cash, test csr 2 cheats.