I decided to stop grinding the Freeway Blast race. I realized that for me, it's better to find the most fun way to grind rather than the most quick way.
So I've been testing the upgrade setups for my cars to see how well they do using the street races, starting with my lowest class cars. For my Class D cars, I have setups from Class C to A. I've tested the 240SX, Miata and now I'm in the middle of doing the Corolla. So far, I've made a little over a million credits. I can only imagine how much money I'll have once I'm all done. Sure, this may take longer than grinding with the Aventador but this is much more enjoyable. I may start doing something similar to this for FM4 since I think Rivals can be a chore at times.