Only get to know at S class final? Nah, it is not possible with regular car because every boss race for car, boses uses same super nitro. Those cars are selled for cash. And best part, all Boss cars are made useless in normal races. D class car is given out as C class car. C class car as B class car and they come maxed out, so you cant even upgrade in higher tier. You just buy design and maybe some special event in future. I have bought 2 cheap ones and it is wasted money.
That's much harder than getting Shep's 570S, since you have more options to get his car but still need you car maxed with the best augments and good experience in 4.1.
I skipped Tyler's Escort by buying super nitro. The next two ones were easier and I made it without the super nitro. Now I'm struggeling in Tier A because my 959 can't get faster than 14 seconds on 4.1.
You can get gold from crates and for crates you need keys which you can get from daily races and daily rewards. Problem is that people complain that it's too slow. Reason for that is, the faster you play, the more you complain about the slow stuff. I have camped in Tier D for three months and I didn't complain.